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[vsnet-grb-info 40764] GRB 251116A: Fermi GBM Final Real-time Localization
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42700 SUBJECT: GRB 251116A: Fermi GBM Final Real-time Localization DATE: 25/11/16 02:10:44 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 02:00:04 UT on 16 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251116A (trigger 784951209.245526 / 251116083). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 27.3, Dec = -24.8 (J2000 degrees, equivalent to J2000 01h 49m, -24d 48'), with a statistical uncertainty of 4.5 degrees. The angle from the Fermi LAT boresight is 30.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251116083/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251116083/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251116083/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42700. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40763] LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42699 SUBJECT: LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap DATE: 25/11/15 21:10:03 GMT FROM: antier(a)ijclab.in2p3.fr P. Hello (IJCLAB), D. Akl (NYUAD), S. Antier (IJCLAB), A. Klotz (IRAP), M. Mazek (FZU), M. Pillas (IAP), O. Pyshna (Caltech), C. Andrade (UMN), M. Coughlin (UMN), C. Douzet (IJCLAB), S. Karpov (FZU), T. duLaz (Caltech), R. LeMontagner (IJCLAB), C. Limonta (OCA), Y. Rajabov (UBAI), D. Turpin (CEA-AIM) on behalf of the GRANDMA collaboration: We observed the S251112cm (Initial, as provided by GCN 42650, LVK collaboration) sky localization area with wide field telescopes TAROT/TRE, TAROT/TCH, TAROT/TCA, FRAM-FZU,together with the 60 cm telescope at Les Makes Observatory. Observations started at 2025-11-12 17:14 UTC, e.g 1h56 after the trigger time and during 14h. We used the SkyPortal application (skyportal.io) and associated services to monitor this observational campaign (Coughlin et al. 2018, 2023). Our sensivity map of the GW sky localization area has been computed using Pillas et al., 2025 and is accessible at https://grandma-owncloud.ijclab.in2p3.fr/index.php/s/TqGach7PpbM4d3K. We covered 22% of the Initial sky localization area (Bayestar, GCN 42650 LVK collaboration) and 16% of the Updated sky localization area (Bilby, GCN 2690, LVK collaboration). Preliminary analysis did not reveal any clear candidate that can be associated to the event (with limit magnitudes ranging from 17 to 21 mag in r-band at 5 sigma). We re-conducted a second epoch of observations the day after. All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2025). Images obtained were calibrated using the PanSTARRS DR1 catalog. We are currently investigating candidates reported by other collaborations. GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42699. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40762] LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42698 SUBJECT: LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA DATE: 25/11/15 13:54:03 GMT FROM: Yodgor Rajabov at UBAI <rajabov(a)astrin.uz> O. Burkhonov, Y. Rajabov, Y. Tillayev (UBAI), P. Hello (IJCLAB), A. Klotz (IRAP), M. Coughlin (UMN), S. Karpov (FZU), M. Pillas (IAP), M. Mazek (FZU ), S. Antier (IJCLAB), O. Pyshna (Caltech) on behalf of GRANDMA: We detected transient event 2025adht in RA_J2000=12:00:24.3431, Dec_J2000=+49:02:51.7 reported by (GCN 42677 Anand et al., Franz GCN 42675 et al.,). Observations were carried out at the 1.5-meter telescope Maidanak Observatory by using 4Kx4K SNUCAM CCD. All observations were taken using a Bessel R filter. The observations started at 2025-11-15T00:13:15 UTC and ended at 2025-11-15T00:40:17 UTC. A total of 6 CCD images with an exposure of 300 seconds were obtained. Despite the fact that this object is located far from the equator, we checked for the presence of small bodies in this region using the small body database from 14 November 2025. The check was negative. Cross-identification results indicated the same galaxy without any transient events: DSS J120024.56+490254.3, WISEA J120024.53+490254.1, and GALEXASC J120024.49+490252.9. We analyzed our data using our standard pipeline and with STDWeb/STDPipe (Karpov, 2025). We present stacked results after galaxy soustraction. MJD | DATE-OBS | MAG |M_ERR|U.L.|FILTER| Telescope| MAG system -------------------------------------------------------------------------------------- 60994.00920139 | 2025-11-15 00:29 | 21.54|0.1|22.10|R|UBAI/AZT-22|Vega, Gaia DR3 Which has an equivalent using PS1 of 21.64+/- 0.1 in sdssr using PS1 (color term 0.13). More observations are planned. GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/) Maidanak astronomical observatory (MAO) is an observational facility of the Ulugh Beg Astronomical Institute (UBAI), Uzbekistan Academy of Sciences (http://maidanak.uz/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42698. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40761] GRB 251115A: Tiled Swift observations
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42697 SUBJECT: GRB 251115A: Tiled Swift observations DATE: 25/11/15 13:11:54 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the Fermi/LAT GRB 251115A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/xrt_products/TILED_GRB00140 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42697. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40760] GRB 251115A: Fermi-LAT detection
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42696 SUBJECT: GRB 251115A: Fermi-LAT detection DATE: 25/11/15 12:51:17 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca(a)unitn.it> E. Bissaldi (Politecnico and INFN Bari), A. Holzmann Airasca (UniTrento and INFN Bari), R. Gupta (NASA GSFC), T. Nymark (KTH), F. Longo (University and INFN, Trieste) and S. Lopez (CNRS / IN2P3) report on behalf of the Fermi-LAT Collaboration: On November 15, 2025, Fermi-LAT detected high-energy emission from GRB 251115A, which was also detected by Fermi-GBM (trigger 784869607 / 251115139, GCN 42692) and Global MASTER (GCN 42694). The best LAT on-ground location is found to be: RA, Dec = 330.18, -9.18 (J2000) with an error radius of 0.36 deg (90 % containment, statistical error only). This was 80 deg from the LAT boresight at the time of the GBM trigger (T0 = 03:20:02.67 UT). The data from the Fermi-LAT shows a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0 - 600 s after the GBM trigger is (1.04 ± 0.34) E-5 ph/cm2/s. The estimated photon index above 100 MeV is -2.5 ± 0.4. The highest-energy photon is a 1.6 GeV event which is observed ~ 490 seconds after the GBM trigger. A Swift ToO has been approved for this burst. The Fermi-LAT point of contact for this burst is Tanja Kramer Nymark (tanjan(a)kth.se) The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. View this GCN Circular online at https://gcn.nasa.gov/circulars/42696. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40759] GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42695 SUBJECT: GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis DATE: 25/11/15 11:31:15 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Nicolas Dagoneau (CEA), Chen-Wei Wang (IHEP), Frédéric Piron (LUPM), Jean-Luc Atteia (IRAP) Using the event-by-event data downloaded through the X-band ground station, we report the preliminary ECLAIRs-GRM joint analysis of GRB 251013C (SVOM burst-id sb2525101311, GCN 42222) detected at T0 = 2025-10-13T17:39:42, which was also detected Fermi/GBM (GCN 42259). The refined analysis for ECLAIRs only was reported in GCN 42292. T90s are given in the table below for both ECLAIRs and GRM. | Instrument | Energy Range | T90 (s) | |-----------------|------------------|-----------------| | ECLAIRs | 4–120 keV | 19 (-2 / +5) s | | GRM | 50–300 keV | 13 (-1 / +4) s | The ECLAIRs-GRM joint time-averaged spectrum (T0-0.83 s to T0+17.70 s) in the 8-5000 keV energy range is best fitted by a power-law model with a photon index of 1.55 -0.03/+0.02. With this model, the total 10-1000 keV fluence is (4.58 +/- 0.18)e-06 erg/cm^2. From the likelihood profile of Epeak obtained by iteratively fitting a cutoff power-law model with a frozen Epeak parameter, we derived a 95% confidence level lower limit of approximately 480 keV, which is consistent with the value measured by Fermi (GCN 42259). With a redshift of z = 0.572 (GCN 42227), the burst isotropic energy Eiso (from 1 keV to 10 MeV in its rest frame) is 5.6e51 erg, which makes this GRB consistent with type I GRBs in the 'Amati' relation diagram (Amati et al. 2002). All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs-GRM point of contact for this burst is: Nicolas Dagoneau (nicolas.dagoneau AT cea.fr). View this GCN Circular online at https://gcn.nasa.gov/circulars/42695. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40758] Fermi GRB 251115A: Global MASTER-Net observations report
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42694 SUBJECT: Fermi GRB 251115A: Global MASTER-Net observations report DATE: 25/11/15 04:30:41 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 251115A ( Fermi GBM team, GCN 42692) errorbox 41 sec after notice time and 74 sec after trigger time at 2025-11-15 03:21:17 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 64 deg. The sun altitude is -38.6 deg. The galactic latitude b = -47 deg., longitude l = 59 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3042754 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 80 | 2025-11-15 03:21:17 | MASTER-OAFA | (22h 03m 35.41s , -07d 54m 09.9s) | C | 10 | 18.6 | 101 | 2025-11-15 03:21:33 | MASTER-OAFA | (22h 03m 35.36s , -07d 54m 09.6s) | C | 20 | 19.0 | 141 | 2025-11-15 03:22:09 | MASTER-OAFA | (22h 12m 15.81s , -08d 11m 40.7s) | C | 30 | 19.4 | 178 | 2025-11-15 03:22:45 | MASTER-OAFA | (22h 12m 15.80s , -08d 11m 40.4s) | C | 30 | 19.4 | 219 | 2025-11-15 03:23:21 | MASTER-OAFA | (22h 12m 15.79s , -08d 11m 40.4s) | C | 40 | 19.5 | 270 | 2025-11-15 03:24:07 | MASTER-OAFA | (22h 12m 15.78s , -08d 11m 40.0s) | C | 50 | 19.7 | 331 | 2025-11-15 03:25:03 | MASTER-OAFA | (22h 12m 15.78s , -08d 11m 40.0s) | C | 60 | 19.8 | 658 | 2025-11-15 03:30:00 | MASTER-OAFA | (22h 18m 22.95s , -04d 21m 04.4s) | C | 120 | 20.0 | 794 | 2025-11-15 03:32:06 | MASTER-OAFA | (22h 18m 22.96s , -04d 21m 04.5s) | C | 140 | 20.0 | 955 | 2025-11-15 03:34:32 | MASTER-OAFA | (22h 18m 22.96s , -04d 21m 04.4s) | C | 170 | 20.0 | 1076 | 2025-11-15 03:37:28 | MASTER-OAFA | (22h 18m 22.99s , -04d 21m 04.2s) | C | 60 | 19.5 | 1141 | 2025-11-15 03:38:34 | MASTER-OAFA | (22h 18m 23.03s , -04d 21m 04.4s) | C | 60 | 19.5 | 1207 | 2025-11-15 03:39:39 | MASTER-OAFA | (22h 18m 23.03s , -04d 21m 04.4s) | C | 60 | 19.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42694. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40757] LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42693 SUBJECT: LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume DATE: 25/11/15 03:46:56 GMT FROM: David Cook at Caltech/IPAC-NED <dcook(a)ipac.caltech.edu> David O. Cook (Caltech/IPAC), Rick Ebert (Caltech/IPAC), George Helou (Caltech/IPAC), Joseph M. Mazzarella (Caltech/IPAC), Marion Schmitz (Caltech/IPAC), and Leo Singer (NASA/GSFC) On behalf of the NASA/IPAC Extragalactic Database (NED) Team. We spatially cross-matched the LVK S251112cm-4-Update sky localization with the NED Local Volume Sample (NED-LVS; Cook et al. 2023; https://ned.ipac.caltech.edu/NED::LVS/) which is a subset of NED with a redshift or redshift-independent distance less than 1000 Mpc. We find 9047 galaxies within the 90% containment volume, and we list here the top 20 galaxies sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full or top 20 list of galaxies in the 90% volume go either to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/ or click on the following links: Full List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S251112cm/4 Top 20 List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S251112cm/4/20 The NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic follow-up observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D * P_SFR; and specific star formation rate, P_3D * P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume. | objname| ra| dec|objtype| DistMpc|DistMpc_unc| m_NUV| m_NUV_unc| m_Ks| m_Ks_unc| m_W1| m_W1_unc| P_3D|P_3D_LumW1| |-------------------------|--------------|--------------|-------|-----------|-----------|------------|------------|------------|------------|------------|------------|--------|----------| | IC 1633| 17.48145| -45.93116| G| 96.06| 3.43| null| null| 8.396| 0.025| 8.999| 0.006|8.02e-06| 1.10e-08| | IC 0564| 146.58792| 3.07130| G| 75.75| 2.62| null| null| 10.033| 0.035| 10.010| 0.006|2.41e-05| 8.10e-09| | IC 1464B| 345.79587| -8.98909| G| 105.88| 0.59| null| null| 10.015| 0.036| 9.741| 0.006|8.31e-06| 6.98e-09| |WISEA J100012.04+093856.0| 150.05020| 9.64890| G| 78.82| 0.30| null| null| 11.073| 0.096| 10.233| 0.006|2.04e-05| 6.04e-09| | UGC 05226| 146.51479| 4.40348| G| 66.86| 15.78| 18.763| 0.092| 10.211| 0.041| 10.083| 0.089|2.21e-05| 5.42e-09| | ESO 197- G 021| 31.13585| -52.17213| G| 87.54| 0.39| null| null| 9.099| 0.026| 9.375| 0.006|6.49e-06| 5.21e-09| | MCG -01-24-010| 140.09147| -7.88074| G| 53.94| 2.54| 15.885| 0.007| 10.054| 0.032| 9.821| 0.030|2.49e-05| 5.05e-09| | MRK 0421| 166.11381| 38.20883| G| 85.15| 33.84| null| null| 9.996| 0.029| 9.258| 0.005|5.81e-06| 4.92e-09| | IC 1464A| 345.80030| -8.99285| G| 107.09| 0.04| null| null| 11.963| 0.011| 10.070| 0.006|7.57e-06| 4.81e-09| | NGC 7364| 341.10153| -0.16213| G| 76.48| 8.25| 16.366| 0.001| 9.478| 0.028| 9.218| 0.003|6.74e-06| 4.80e-09| | IC 1471| 347.18676| -12.63948| G| 83.00| 17.58| 17.246| 0.027| 10.334| 0.035| 10.290| 0.006|1.49e-05| 4.63e-09| | ESO 243- G 051| 17.83050| -45.93204| G| 94.78| 0.36| 17.032| 0.008| 10.015| 0.031| 10.036| 0.006|8.85e-06| 4.53e-09| | NGC 2951 NED01| 144.92019| -0.23515| G| 70.23| 0.53| 18.380| 0.003| 10.498| 0.057| 10.537| 0.004|2.33e-05| 4.19e-09| | IC 2471| 141.30071| -6.82994| G| 58.50| 12.39| 18.644| 0.054| 9.949| 0.034| 10.076| 0.006|2.19e-05| 4.12e-09| | NGC 3070| 149.52893| 10.35980| G| 60.25| 5.89| 18.225| 0.068| 9.260| 0.030| 9.503| 0.006|1.21e-05| 4.12e-09| | ESO 197- G 018| 30.62846| -50.93160| G| 110.00| 24.82| null| null| 9.612| 0.028| 9.779| 0.006|4.35e-06| 3.80e-09| | NGC 2951 NED02| 144.91664| -0.23524| G| 71.31| 0.04| 18.383| 0.003| 12.873| 0.052| 10.592| 0.004|2.13e-05| 3.75e-09| | ESO 243- G 045| 17.26888| -45.77349| G| 82.00| 9.44| 18.245| 0.024| 9.713| 0.035| 9.964| 0.006|9.07e-06| 3.71e-09| | IC 0563| 146.58473| 3.04574| G| 57.00| 22.05| 16.948| 0.010| 10.810| 0.054| 10.328| 0.027|2.54e-05| 3.62e-09| | ESO 197- G 010| 28.30237| -49.56039| G| 76.43| 6.54| null| null| 8.882| 0.034| 9.458| 0.006|6.17e-06| 3.50e-09| Table 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S251112cm sorted by the joint probability of 3D position and WISE W1 luminosity (P_3D * P_LumW1). Galaxy is the NED preferred name. RA and Dec are the Equatorial coordinates in degrees (J2000). Objtype is the object type of the galaxy candidate. Distance is the distance to the galaxy in Mpc. m_NUV and mErr_NUV are the apparent magnitude and error from GALEX. m_Ks and mErr_Ks are the apparent magnitude and error from 2MASS. m_W1 and mErr_W1 are the apparent magnitude and error from AllWISE. P_3D is the probability that the galaxy is in the volume given the distance of GW event. P_3D_LumW1 is the joint probability within the volume weighted by the WISE1 luminosity of the galaxy (P_3D * P_LumW1). View this GCN Circular online at https://gcn.nasa.gov/circulars/42693. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40756] GRB 251115A: Fermi GBM Final Real-time Localization
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42692 SUBJECT: GRB 251115A: Fermi GBM Final Real-time Localization DATE: 25/11/15 03:30:39 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 03:20:02 UT on 15 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251115A (trigger 784869607.66655 / 251115139). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 334.5, Dec = -4.5 (J2000 degrees, equivalent to J2000 22h 18m, -4d 30'), with a statistical uncertainty of 4.1 degrees. The angle from the Fermi LAT boresight is 80.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42692. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40755] LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42691 SUBJECT: LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates DATE: 25/11/15 03:16:35 GMT FROM: Xander J Hall at Carnegie Mellon University <xjh(a)andrew.cmu.edu> Xander J. Hall (CMU), Tomás Cabrera (CMU), Julius Gassert (CMU/LMU), Lei Hu (UPenn), Antonella Palmese (CMU), Brendan O’Connor (CMU), Igor Andreoni (UNC), on behalf of the Gravitational Wave MultiMessenger Astronomy DECam Survey (GW-MMADS) team report: We observed the high probability area of the LVK gravitational wave candidate S251112cm (GCN 42650) using the wide-field Dark Energy Camera (DECam) on the 4m Blanco telescope. Observations started at 2025-11-14 00:03 UTC (Prop ID: 2023B-851374; PI Palmese & Andreoni) and focused on the southern lobe of the Bilby skymap (GCN 42690; 30% of the total posterior probability). We run the SFFT difference imaging (Hu et al. 2022) on the available images, filter out likely stars and moving objects, and then visually inspect the remaining transients. We report on TNS 54 new transients within the observed area, and we report here select transients: | id | AT name | ra | dec | discovery_date (UT) | mag_g | mag_g_err | mag_g-mag_i | NED separation | | ------------------------ | ---------- | ---------- | ---------- | ----------------------- | ------ | ----- | ----- | ----- | | T202511140018095m335115* | AT 2025adjp | 4.539622 | -33.854284 | 2025-11-14 02:08:26.016 | 21.13 | 0.04 | 0.25 | 92.7", 94.5", 94.6" | T202511140030086m410443 | AT 2025adkl | 7.535766 | -41.078709 | 2025-11-14 02:13:43.104 | 20.91 | 0.03 | -0.14 | 90.5" *This transient is within 2' of three NED in-volume galaxies. We note while both of these transients are within 2' of a NED in-volume galaxy (GCN 42653), they are both near galaxies with LS DR9 photo-z > 0.12 which would place them outside of the volume. Further analysis is underway. We thank the CTIO and NOIRLab staff for supporting these observations and the data calibration. View this GCN Circular online at https://gcn.nasa.gov/circulars/42691. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40754] LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42690 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate DATE: 25/11/15 00:41:29 GMT FROM: Colm Talbot at Princeton University <talbotcolm(a)gmail.com> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S251112cm (GCN Circular 42650). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,1, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S251112cm For the Bilby.multiorder.fits,1 sky map, the 90% credible region is 1681 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 93 +/- 27 Mpc (a posteriori mean +/- standard deviation). The false alarm rate, as estimated by the MBTA SSM analysis pipeline with an updated background model, has been updated to about one in 4 years. The online search for sub-solar-mass regions is covered by two independent pipelines: MBTA SSM and GstLAL SSM [2]. For the parameter space relevant to the present candidate, only MBTA SSM provides online coverage; therefore, the candidate was triggered solely by MBTA SSM. For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 [2] https://emfollow.docs.ligo.org/userguide/analysis/index.html#false-alarm-ra… View this GCN Circular online at https://gcn.nasa.gov/circulars/42690. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40753] GRB 251113A: Glowbug gamma-ray detection
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42689 SUBJECT: GRB 251113A: Glowbug gamma-ray detection DATE: 25/11/14 22:40:15 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251113A, which was also detected by Fermi/GBM (GCN 42671, 42672) and AstroSat/CZTI (GCN 42688). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-11-13 17:37:28.512 with a duration of 24.6 s and a total significance of about 82 sigma. The light curve comprises three primary peaks at ~T0+8s, +12s, and +18s. Low-level emission may be present up to ~T0+37s. Note that data from ~T0+22s to T0+26s suffered from deadtime in various detectors. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42689. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40752] GRB 251113A: AstroSat CZTI detection
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42688 SUBJECT: GRB 251113A: AstroSat CZTI detection DATE: 25/11/14 21:27:07 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Goyal (IITB), A. Arya (IITB), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 251113A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42671). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-11-13 17:37:42.84 UTC. The measured peak count rate associated with the burst is 208 (+40, -21) counts/s above the background in the combined data of all quadrants, with a total of 2657 (+431, -393) counts. The local mean background count rate was 269 (+4, -5) counts/s. Using cumulative rates, we measure a T90 of 23 (+2, -5) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-13 17:37:42.35 UTC. The measured peak count rate associated with the burst is 350 (+68, -53) counts/s above the background in the combined data of all quadrants, with a total of 4325 (+900, -914) counts. The local mean background count rate was 1169 (+11, -11) counts/s. We measure a T90 of 22 (+2, -4) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42688. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40751] GRB 251114B: Fermi GBM Final Real-time Localization
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42687 SUBJECT: GRB 251114B: Fermi GBM Final Real-time Localization DATE: 25/11/14 20:49:04 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 20:38:30 UT on 14 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251114B (trigger 784845515.202048 / 251114860). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 160.1, Dec = -85.2 (J2000 degrees, equivalent to J2000 10h 40m, -85d 12'), with a statistical uncertainty of 3.5 degrees. The angle from the Fermi LAT boresight is 57.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114860/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114860/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114860/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42687. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40750] GRB 251112A: Swift-BAT refined analysis
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42686 SUBJECT: GRB 251112A: Swift-BAT refined analysis DATE: 25/11/14 20:37:19 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> D. Sadaula (GSFC/UMBC), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), A. Mei (INAF-OAB) M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 251112A (trigger #1413695) (Mei, et al., GCN Circ. 42656). The BAT ground-calculated position is RA, Dec = 274.081, 24.158 deg which is RA(J2000) = 18h 16m 19.5s Dec(J2000) = +24d 09' 28.8" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted BAT light curve shows multi-peaked emission starting ~T-28 sec. T90 (15-350 keV) is 55.42 +- 6.65 sec (estimated error including systematics). The time-averaged spectrum from T-28.30 to T+32.38 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.77 +- 0.75, and Epeak of 48.4 +- 11.9 keV (chi squared 86.37 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 7.6 +- 0.9 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T+1.05 sec in the 15-150 keV band is 0.7 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.86 +- 0.15 (chi squared 94.39 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1413695 View this GCN Circular online at https://gcn.nasa.gov/circulars/42686. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40749] Konus-Wind detection of GRB 251108C
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42685 SUBJECT: Konus-Wind detection of GRB 251108C DATE: 25/11/14 20:07:42 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 251108C (AstroSat-CZTI detection: Salunke et al., GCN 42664; IPN triangulation: Kozyrev et al., GCN 42680) triggered Konus-Wind at T0=83283.415 s UT (23:08:03.415). The burst light curve shows a multipeaked structure which starts at ~T0-0.2 s and has a total duration of ~8.5 s. The emission is seen up to ~6 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251108_T83283/ As observed by Konus-Wind, the burst had a fluence of 1.51(-0.19,+0.23)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0-0.172 s, of 1.23(-0.23,+0.26)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.05(-0.10,+0.11) and Ep = 1415(-316,+464) keV (chi2 = 55/69 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -1.7 (chi2 = 53/68 dof). The spectrum near the maximum count rate (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model with alpha = -0.96(-0.17,+0.22) and Ep = 2202(-834,+1554) keV (chi2 = 26/30 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -1.4 (chi2 = 26/29 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/42685. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40748] Fermi trigger No 784717756: Global MASTER-Net observations report
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42684 SUBJECT: Fermi trigger No 784717756: Global MASTER-Net observations report DATE: 25/11/14 18:31:18 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB251113.38 (trigger No 784717756,18h 51m 24.00s , +17d 07m 58.8s, R=28.6) errorbox 58396 sec after notice time and 58428 sec after trigger time at 2025-11-14 01:22:59 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 64 deg. The sun altitude is -25.2 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB251113.38 errorbox 1 days 30851 sec after notice time and 1 days 30882 sec after trigger time at 2025-11-14 17:43:53 UT, with upper limit up to 16.8 mag. The observations began at zenith distance = 75 deg. The sun altitude is -42.9 deg. The galactic latitude b = 7 deg., longitude l = 49 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3041181 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 58488 | 2025-11-14 01:22:59 | MASTER-OAFA | (20h 52m 07.43s , +09d 10m 19.0s) | C | 120 | 19.9 | 58624 | 2025-11-14 01:25:05 | MASTER-OAFA | (20h 52m 07.40s , +09d 10m 19.6s) | C | 140 | 20.0 | 58787 | 2025-11-14 01:27:33 | MASTER-OAFA | (20h 52m 07.36s , +09d 10m 20.0s) | C | 170 | 20.0 | 58908 | 2025-11-14 01:30:29 | MASTER-OAFA | (20h 52m 07.34s , +09d 10m 20.1s) | C | 60 | 19.6 | 58974 | 2025-11-14 01:31:35 | MASTER-OAFA | (20h 52m 07.33s , +09d 10m 20.0s) | C | 60 | 19.6 | 59040 | 2025-11-14 01:32:41 | MASTER-OAFA | (20h 52m 07.32s , +09d 10m 20.4s) | C | 60 | 19.5 | 117313 | 2025-11-14 17:43:53 | MASTER-Kislovodsk | (19h 11m 01.28s , +05d 00m 12.1s) | C | 60 | 15.4 | 117313 | 2025-11-14 17:43:53 | MASTER-Kislovodsk | (19h 11m 07.05s , +05d 22m 44.2s) | C | 60 | 15.7 | 117453 | 2025-11-14 17:45:13 | MASTER-Kislovodsk | (18h 14m 55.94s , +24d 10m 07.2s) | C | 180 | 16.4 | 117453 | 2025-11-14 17:45:13 | MASTER-Kislovodsk | (18h 15m 01.21s , +24d 32m 41.2s) | C | 180 | 16.8 | 117653 | 2025-11-14 17:48:33 | MASTER-Kislovodsk | (18h 34m 43.18s , +18d 08m 20.3s) | C | 180 | 16.1 | 117653 | 2025-11-14 17:48:33 | MASTER-Kislovodsk | (18h 34m 49.05s , +18d 30m 54.3s) | C | 180 | 16.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42684. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40747] Konus-Wind detection of GRB 251103A
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42683 SUBJECT: Konus-Wind detection of GRB 251103A DATE: 25/11/14 16:45:00 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 251103A (SVOM-ECLAIRs detection: Hu et al., GCN 42534; Fermi-GBM detection: The Fermi GBM team, GCN 42536; Sonawane and Godwin, GCN 42553; SVOM-GRM detection: Wang et al., GCN 42552; Insight-HXMT/HE detection: Ren et al., GCN 42572) triggered Konus-Wind at T0=17189.335 s UT (04:46:29.335). The burst light curve shows a single pulse which starts at ~T0-0.5 s and has a total duration of ~5.5 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251103_T17189/ As observed by Konus-Wind, the burst had the total fluence of 9.48(-0.93,+1.02)x10^-6 erg/cm2, and the 64-ms peak flux, measured from T0+0.022 s, of 6.52(-2.04,+2.79)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.33(-0.71,+1.08), the high energy photon index beta = -2.21(-0.11,+0.09), the peak energy Ep = 86(-15,+25) keV (chi2 = 86/80 dof). The spectrum near the maximum count rate (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 2 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.97(-0.42,+0.99), the high energy photon index beta = -2.25(-7.75,+0.39), the peak energy Ep = 292(-160,+184) keV (chi2 = 16/18 dof). Assuming the redshift z=0.76 (Izzo et al., GCN 42540) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 1.53(-0.15,+0.16)x10^52 erg, the peak luminosity L_iso is 1.85(-0.58,+0.79)x10^52 erg/s, the rest-frame peak energy of the time-averaged spectrum Ep,i,z is 151(-27,+44) keV and the spectrum near the maximum count rate Ep,p,z is 513(-281,+324) keV. With the obtained estimates, GRB 251103A is inside 68% prediction bands for both the 'Amati' and the 'Yonetoku' relations derived for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021), see http://www.ioffe.ru/LEA/GRBs/GRB251103_T17189/GRB251103A_rest_frame.pdf All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/42683. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40746] LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42682 SUBJECT: LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap DATE: 25/11/14 15:59:20 GMT FROM: Adam Smith at Queen's University Belfast <asmith67(a)qub.ac.uk> A. Smith, M. Nicholl, (QUB), J. Gillanders, S. J. Smart, K. W. Smith, (Oxford), D. R. Young, C. R. Angus, M. D. Fulton, T. Moore, A. Aamer, S. Sim, J. Weston, X. Sheng, D. Magill, P. Ramsden (QUB), S. Srivastav, H. Stevance, F. Stoppa, A. Cooper, J. Tweddle, L. Eastman (Oxford), L. Shingles (GSI/QUB), L. Rhodes (TSI/McGill), L. Denneau, J. Tonry, H. Weiland, R. Siverd (IfA, University of Hawaii), N. Erasmus, W. Koorts (South African Astronomical Observatory), A. Rest (STScI), T.-W. Chen (NCU), C. Stubbs (Harvard), J. Sommer (LMU/QUB), B. Schmidt (ANU): We report observations of the Bilby.fits skymap of the compact binary merger candidate S251112cm (The LIGO-Virgo-Kagra Collaboration, GCN 42650) with the ATLAS telescope system (Tonry et al., 2018, PASP, 13, 164505). ATLAS is a quintuple 0.5m optical telescope survey system (Hawaii x 2, South Africa, Chile, Tenerife) employing three filters, cyan, orange, and ‘clear’. In our primary NASA mission for Near-Earth Object discovery, we cover the entire visible night sky every 24hrs to AB magnitude depths m ~ 19.5, weather and Moon permitting. During focused science operations, we covered part of the accessible skymap of S251112cm. A sequence of quads (4 x 120-sec images) was taken at each pointing position. The images were processed with the ATLAS pipeline, and reference images were subtracted from each one. Transient candidates were identified and run through our standard filtering procedures (Smith et al., 2020, PASP, 132, 1). We covered 665.14 square degrees of the bilby.fits skymap 90% area, and covered a sky region totalling 45.08% of the event's full localisation likelihood, South of declination = 11 degrees. Data acquisition began at MJD 60991.811354 or 2025-11-12 19:28:20 (UTC), 3.5hrs after the LVC Preliminary/Initial notice and 4.2hrs after the merger event at 2025-11-12 15:18:45.362 (UTC). Observations lasted between ~4.2hrs to 41.3hrs after the GW detection. The depths of our images typically reached m_o < 19.5 AB mag. We found 26 transient sources, including 5 previously unreported transients. However, all had been previously detected by ATLAS before the merger event, or reported to the IAU Transient name server (https://www.wis-tns.org) and/or are associated with host galaxies with photometric redshifts beyond z > 0.05. We are reporting all discoveries to the TNS, where they can be tracked, classified, searched, and commented upon. We encourage further information to be reported on the TNS object pages. We checked the ATLAS forced photometry for the 3 GOTO objects reported by Ackley et al. (GCN 42658), and confirmed that all three have flux detected before the S251112cm GW event time. This flux on the individual 30 sec images are each below 5-sigma significance but the combined detections over multiple nights indicate the source was detected. These detections can be checked on ATLAS forced photometry server (Shingles et al. AstroNote 2021-7). The Asteroid Terrestrial-impact Last Alert System (ATLAS) project is primarily funded to search for Near-Earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen's University Belfast, the University of Oxford, the Space Telescope Science Institute, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile. View this GCN Circular online at https://gcn.nasa.gov/circulars/42682. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40745] LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42681 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources DATE: 25/11/14 15:15:33 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> K.L. Page (U. Leicester), P.A. Evans (U. Leicester), J.A. Kennea (PSU), A. Tohuvavohu (Cosmic Frontier Labs), S.B. Cenko (NASA/GSFC), R.A.J. Eyles-Ferris (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), A.A. Breeveld (UCL-MSSL), S. Campana (INAF-OAB), J.J. Delaunay (PSU), M. De Pasquale (University of Messina), S. Dichiara (PSU), P. D’Avanzo (INAF-OAB), A. D’Aì (INAF-IASFPA) , V. D’Elia (ASI-SSDC & INAF-OAR), C. Gronwall (PSU), D. Hartmann (Clemson University), N. Klingler (NASA-GSFC / UMBC / CRESST II), N.P.M. Kuin (UCL-MSSL), S. Laha (NASA/GSFC), S.R. Oates (U. Birmingham), J.P. Osborne (U. Leicester), P. O’Brien (U. Leicester), M.J. Page (UCL-MSSL), G. Raman (PSU) S. Ronchini (PSU), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (U Tor Vergata, INAF) report on behalf of the Swift team: Swift has carried out 105 observations of the LVK error region for the GW trigger S251112cm convolved with the 2MPZ catalogue (Bilicki et al. 2014, ApJS, 210, 9), using the 'BAYESTAR' (version BAYESTAR.fits.gz) GW localisation map. As this is a 3D skymap, galaxy distances were taken into account in selecting which ones to observe. The observations currently span from 7.6 ks to 117 ks after the LVK trigger, and the XRT has covered 12.7 deg^2 on the sky (corrected for overlaps). This covers 1.3% of the probability in the 'BAYESTAR' (version BAYESTAR.fits.gz) skymap, and 20% after convolving with the 2MPZ galaxy catalogue, as described by Evans et al. (2016, MNRAS, 462, 1591). We have detected 20 X-ray sources. Each source is assigned a rank of 1-4 which describes how likely it is to be related to the GW trigger, with 1 being the most likely and 4 being the least likely. The ranks are described at https://www.swift.ac.uk/ranks.php. We have found: * 0 sources of rank 1 * 0 sources of rank 2 * 7 sources of rank 3 * 13 sources of rank 4 RANK 3 sources ============== These are uncatalogued X-ray sources, however they are not brighter than previous upper limits, so do not stand out as likely counterparts to the GW trigger. | Source ID | RA | Dec | Err90 | Detection Flag | | S251112cm_X1 | 11 09 55.90 | +36 08 20.7 | 8.0" | POOR | | S251112cm_X38 | 23 47 03.18 | -28 07 08.2 | 9.5" | POOR | | S251112cm_X53 | 11 08 18.65 | +36 11 04.6 | 8.1" | POOR | | S251112cm_X72 | 12 22 09.27 | +55 52 20.4 | 5.9" | GOOD | | S251112cm_X73 | 01 08 29.26 | -46 59 48.1 | 8.9" | POOR | | S251112cm_X78 | 23 48 35.23 | -28 14 05.5 | 9.8" | POOR | | S251112cm_X79 | 23 48 06.04 | -28 04 35.1 | 12.3" | POOR | RANK 4 sources ============== These are catalogued X-ray sources, showing no signs of outburst compared to previous observations, so they are not likely to be related to the GW trigger. | Source ID | RA | Dec | Err90 | Detection Flag | | S251112cm_X2 | 11 12 06.93 | +35 27 45.6 | 6.8" | GOOD | | S251112cm_X3 | 09 20 46.26 | -08 03 21.4 | 5.5" | GOOD | | S251112cm_X5 | 23 51 37.99 | -28 18 18.1 | 7.6" | POOR | | S251112cm_X50 | 11 37 24.49 | +47 27 44.7 | 7.4" | GOOD | | S251112cm_X51 | 01 08 20.79 | -47 07 36.3 | 7.4" | POOR | | S251112cm_X52 | 01 07 42.60 | -46 54 24.5 | 6.1" | GOOD | | S251112cm_X67 | 11 11 04.66 | +35 13 59.3 | 6.9" | GOOD | | S251112cm_X68 | 22 44 47.97 | -00 06 17.5 | 8.8" | GOOD | | S251112cm_X69 | 02 36 19.70 | -54 51 50.8 | 5.8" | GOOD | | S251112cm_X70 | 13 06 57.05 | +59 58 48.1 | 10.7" | REASONABLE | | S251112cm_X71 | 12 23 00.00 | +55 40 04.4 | 5.1" | GOOD | | S251112cm_X87 | 11 12 01.25 | +37 58 26.3 | 6.1" | GOOD | | S251112cm_X88 | 11 04 27.52 | +38 12 36.6 | 3.5" | GOOD | For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2, and photon index (Gamma)=1.7, unless otherwise stated. The results of the XRT automated analysis, including details of the sources listed above, are online at https://www.swift.ac.uk/LVC/S251112cm This circular is an official product of the Swift XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42681. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40744] IPN triangulation of GRB 251108C
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42680 SUBJECT: IPN triangulation of GRB 251108C DATE: 25/11/14 13:10:56 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, E. Burns on behalf of the IPN, G. Waratkar, J.Joshi, V. Bhalerao, D. Bhattacharya, A. Arya, and S. Vadawale, on behalf of the Astrosat-CZTI team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: The long-duration GRB 251108C (AstroSat-CZTI detection: Salunke et al., GCN 42664) was detected by Konus-Wind, AstroSat (CZTI), and Mars-Odyssey (HEND), at about 83275 s UT (23:07:55). We have triangulated it to a preliminary, 3 sigma error box whose area is 2.13 sq. deg, and its maximum dimension is 40 deg (the minimum one is 5 arcmin). The Sun distance was ~155 deg. This localization may be improved. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB251108_T83283/IPN/ The HEALPix triangulation map is the multi-order HEALPix in units of probability density. The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. View this GCN Circular online at https://gcn.nasa.gov/circulars/42680. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40743] The EP-WXT trigger 01709248221 is likely a flaring star
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42679 SUBJECT: The EP-WXT trigger 01709248221 is likely a flaring star DATE: 25/11/14 12:33:49 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Z. H. Yang, Q. C. Zhao, Z. X. Li, G. L. Huang, J. Y. Cao (IHEP), J. P. Chen (SYSU), Y. J. Yi (BNU), H. Q. Cheng, H. Sun (NAO, CAS), on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709248221 at the time of 2025-11-14T11:16:43, is likely a stellar flare associated with EM* LkCa 4. The estimated flux of the flare is around 8e-11 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 1.6e+32 erg/s. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42679. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40742] Fermi GRB 251114A: Global MASTER-Net observations report
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42678 SUBJECT: Fermi GRB 251114A: Global MASTER-Net observations report DATE: 25/11/14 03:15:50 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 251114A ( Fermi GBM team, GCN 42676) errorbox 101 sec after notice time and 138 sec after trigger time at 2025-11-14 01:15:30 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 60 deg. The sun altitude is -24.0 deg. The galactic latitude b = -22 deg., longitude l = 57 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3041842 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 154 | 2025-11-14 01:15:30 | MASTER-OAFA | (20h 55m 15.88s , +05d 45m 40.4s) | C | 30 | 19.5 | 190 | 2025-11-14 01:16:06 | MASTER-OAFA | (20h 55m 15.85s , +05d 45m 40.8s) | C | 30 | 19.6 | 231 | 2025-11-14 01:16:41 | MASTER-OAFA | (20h 55m 15.85s , +05d 45m 41.1s) | C | 40 | 19.7 | 282 | 2025-11-14 01:17:28 | MASTER-OAFA | (20h 55m 15.83s , +05d 45m 41.5s) | C | 50 | 19.8 | 343 | 2025-11-14 01:18:24 | MASTER-OAFA | (20h 55m 15.83s , +05d 45m 42.1s) | C | 60 | 19.9 | 648 | 2025-11-14 01:22:59 | MASTER-OAFA | (20h 52m 07.43s , +09d 10m 19.0s) | C | 120 | 19.9 | 784 | 2025-11-14 01:25:05 | MASTER-OAFA | (20h 52m 07.40s , +09d 10m 19.6s) | C | 140 | 20.0 | 947 | 2025-11-14 01:27:33 | MASTER-OAFA | (20h 52m 07.36s , +09d 10m 20.0s) | C | 170 | 20.0 | 1068 | 2025-11-14 01:30:29 | MASTER-OAFA | (20h 52m 07.34s , +09d 10m 20.1s) | C | 60 | 19.6 | 1134 | 2025-11-14 01:31:35 | MASTER-OAFA | (20h 52m 07.33s , +09d 10m 20.0s) | C | 60 | 19.6 | 1200 | 2025-11-14 01:32:41 | MASTER-OAFA | (20h 52m 07.32s , +09d 10m 20.4s) | C | 60 | 19.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42678. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40741] LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42677 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility DATE: 25/11/14 02:20:19 GMT FROM: Shreya Anand <shreyasahasram08(a)gmail.com> S. Anand (Stanford), R. Stein (UMD), X. J. Hall (CMU), V. Swain (IIT-B), A. Saikia (IIT-B), T. Mohan (IIT-B), V. Bhalerao (IIT-B), D. Cook (Caltech/IPAC), A. Singh (SU), M. M. Kasliwal (Caltech), E. C. Bellm (UW), M. Coughlin (UMN), T. du Laz (Caltech), V. Karambelkar (Columbia), G. Waratkar (Caltech), I. Andreoni (UNC), A. Palmese (CMU) report, on behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: We observed the localization region of the LVK sub-solar mass candidate S251112cm (GCN 42650) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2025-11-12 09:21 UTC, approximately 18 hours after merger, covering 38.3% of the probability within the 90% credible region of the LVK skymap in g- and r-bands. This estimate accounts for chip gaps. Each exposure was 300s with a median r-band depth of 21.14 mag. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019), removing candidates with history of variability prior to the merger time. Because of the nature of the GW trigger as a sub-solar mass merger candidate, we do not exclude any candidates that may be consistent with being young stripped envelope supernovae (SESNe). Disk fragmentation or core fissioning in SESNe may lead to the formation of subsolar mass neutron stars (Metzger et al. 2024, Kasliwal et al. 2025). After filtering, 8 transient candidates remain, all within the 95.0% localization of the skymap. Candidates marked as FAR have redshifts from Legacy Survey or from SDSS (shown below). Redshift lower limits come from Legacy Survey (l95; a conservative lower limit on the photometric redshift). We list the 8 candidates found in the table below: | ZTF Name | RA (deg) | DEC (deg) | MJD | Filt | Mag | MagErr | Redshift | Note | | ------------- | ---------- | --------- | -------- | ---- | ----- | ------ | --------------------------------------- | ---------------------------------------- | | ZTF25aceekrn* | 180.101460 | 49.047764 | 60992.43 | g | 21.04 | 0.22 | photo-z=0.14 (LS); photo-z=0.189 (SDSS) | FAR | | ZTF25aceekwp | 181.804049 | 55.653636 | 60992.44 | g | 21.23 | 0.20 | photo-z>0.24 (LS) | FAR | | ZTF25aceelgz | 190.811137 | 57.328886 | 60992.47 | g | 21.15 | 0.13 | spec-z=0.476 (SDSS) | AGN-like; w1-w2=0.97 | | ZTF25aceelbm | 169.544486 | 41.094776 | 60992.41 | g | 21.20 | 0.23 | photo-z=0.21 (LS); photo-z=0.24 (SDSS) | FAR | | ZTF25aceemla | 185.395941 | 56.586289 | 60992.46 | r | 21.25 | 0.23 | photo-z>0.28 (LS) | FAR | | ZTF25aceekzz | 169.076786 | 39.863435 | 60992.41 | g | 21.32 | 0.26 | photo-z=0.528 (LS) | AGN-like; ZTF pre-detections; w1-w2=1.13 | | ZTF25aceelmh | 184.916369 | 57.167778 | 60992.47 | g | 21.61 | 0.22 | photo-z>0.41 (LS); photo-z=0.42 (SDSS) | FAR | | ZTF25aceempu | 169.569004 | 35.985827 | 60992.49 | r | 21.60 | 0.21 | photo-z>0.23 (LS) | FAR | *ZTF25aceekrn (AT 2025adht) was previously reported by the TROVE team (GCN 42675) with a photo-z=0.11 +/- 0.07 (nominally consistent with the LVK distance posterior). A spectrum can help resolve this discrepancy. None of the other candidates reported here warrant additional follow-up. All candidates have been reported to the Transient Name Server, and some are pending assignment of a TNS name. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Award #2407588 and a partnership including Caltech, USA; Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; University of Wisconsin at Milwaukee, USA; Cornell University, USA; Drexel University, USA; University of North Carolina at Chapel Hill, USA; Institute of Science and Technology, Austria; National Central University, Taiwan; Operations are conducted by Caltech's Optical Observatory (COO) and Caltech/IPAC. GROWTH acknowledges the generous support of the NSF under PIRE Grant No 1545949. Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski (Duev et al. 2019). The GROWTH India Telescope (GIT, Kumar et al., 2022) is set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. Its operations are partially supported by funding from the IIT Bombay alumni batch of 1994. The Fritz and SkyPortal projects acknowledge the generous support of The Gordon and Betty Moore Foundation. View this GCN Circular online at https://gcn.nasa.gov/circulars/42677. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40740] GRB 251114A: Fermi GBM Final Real-time Localization
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42676 SUBJECT: GRB 251114A: Fermi GBM Final Real-time Localization DATE: 25/11/14 01:23:52 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 01:13:11 UT on 14 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251114A (trigger 784775596.257482 / 251114051). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 312.9, Dec = 9.0 (J2000 degrees, equivalent to J2000 20h 51m, 9d 00'), with a statistical uncertainty of 4.2 degrees. The angle from the Fermi LAT boresight is 82.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114051/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114051/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114051/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42676. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40739] LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42675 SUBJECT: LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates DATE: 25/11/13 22:30:11 GMT FROM: Noah Franz at University of Arizona/Steward Observatory <noahfranz13(a)gmail.com> N. Franz (U. Arizona), N. Vieira (Northwestern), C. D. Kilpatrick (Northwestern), D. J. Sand (U. Arizona), B. Subrayan (U. Arizona), G. Hosseinzadeh (UC San Diego), M. Shrestha (Monash U), K. D. Alexander (U. Arizona), W. Fong (Northwestern), report on behalf of the TROVE collaboration: We analyzed candidate counterparts to the LIGO/Virgo/KAGRA (LVK) gravitational wave event S251112cm (GCN 42650) using the Multi-messenger Tool for Rapid Object Vetting and Examination (TROVE). We searched within the 95th percentile localization region for candidate optical counterparts in host galaxies at the approximate luminosity distance of S251112cm. We further crossmatch to minor planet and point source catalogs and rule out sources that do not appear photometrically similar to kilonova light curves. For additional details, see the vetting procedures described in N. Franz, et al., 2025, arXiv:2510.17104. Below, we report all candidates that remain viable after running our vetting procedure using publicly available information on all publicly reported sources, to date, on the Transient Name Server (TNS). We include their TNS identifier, coordinates, cumulative probability at the coordinate location in the latest LVK map, most likely host redshift, most recent magnitude, and the initial reporting group. Candidates are ranked using a scoring procedure designed to identify kilonova counterparts to GW events (N. Franz, et al., 2025, arXiv:2510.17104). The reported candidates are not clearly identified as kilonovae, but we note that the progenitor system of S251112cm is poorly constrained given the exceptional attributes of the event as reported by LIGO: a probability of the system containing a neutron star < 8%, probability of containing a sub-solar mass object >99%, and a chirp mass in the range 0.1 to 0.87 solar masses. | TNS Name | RA [HMS] | Dec [DMS] | Localization Probability Contour | Most likely Host-z | Most recent public magnitude | Discovery Survey | Comments | | ------- | ------ | ------- | ------- | ------- | ------- | ------- | ------- | | AT2025adht | 12:00:24.350 |+49:02:51.95 | 0.83 | 0.11 +/- 0.07 (photo-z) | g=21.4 +/- 0.2 | ZTF | | | AT2025adgp | 01:47:46.202 | -51:49:25.52 | 0.20 | 0.06 +/- 0.02 (photo-z) | o=19.1 +/- 0.05 | BlackGEM | ATLAS pre-detection ~6 hours before S251112cm. This candidate was initially presented in GCN42663 and the ATLAS pre-detections were noted in GCN 42666. | | AT2025adhf | 02:43:44.411 | -55:19:06.44 | 0.15 | 0.11 +/- 0.02 (photo-z) | o=19.22 +/- 0.05 | ATLAS | ATLAS pre-detections in the ~week leading up to S251112cm. | | AT2025adhs | 04:12:56.396 | -54:11:46.41 | 0.09 | 0.04 (spec-z) | o=20.71 +/- 0.22 | BlackGEM | | We encourage additional follow up of these candidates to determine whether they remain viable counterparts to S251112cm. We note that there are 10 other transients reported to the TNS in the 95% localization region that we rule out for other reasons (e.g., excessive pre-detections, incorrect host distance as compared to S251112cm, etc.): AT2025adhj, AT2025addc, AT2025adhr, AT2025adhu, AT2025adhg, AT2025addb, AT2025adhh, AT2025adda, AT2025adhe, AT2025adgq. View this GCN Circular online at https://gcn.nasa.gov/circulars/42675. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40738] LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42674 SUBJECT: LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region DATE: 25/11/13 20:12:23 GMT FROM: Julius Gassert at Ludwig-Maximilians-Universität München <julius.gassert(a)campus.lmu.de> Julius Gassert (CMU/LMU), Malte Busmann (LMU), Xander J. Hall (CMU), Brendan O’Connor (CMU), Daniel Gruen (LMU), and Antonella Palmese (CMU) report: We observed a sample of 19 DESI galaxies, ranked by 3D position and brightness following the methodology laid out in Hall et al. (2025), in the sky localization region of gravitational wave event S251112cm (GCN 42650) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i, and J bands simultaneously. Observations started at 2025-11-12T17:43 (UT). Typical three-sigma limits for point sources are r, i ~ 21, and the field of view is 7’x7’. We do not identify any candidate GW counterpart in difference imaging with respect to Legacy Survey and PS1 data. The coordinates of the observed targets are listed below. | R.A. | dec | |---|---| | 164.426910134 | 37.65453732955 | | 165.5240393492 | 38.78722513647 | | 167.4811243685 | 36.94655132258 | | 173.5605908567 | 49.0431665104 | | 182.4385674509 | 56.52359456357 | | 182.8894005861 | 57.73745323273 | | 186.0084874694 | 58.38519262405 | | 196.9032263873 | 60.15719529696 | | 197.1937364898 | 62.27166824173 | | 250.834423606 | 70.63254712505 | | 341.1015299287 | -0.162034769873 | | 341.5808358893 | 3.210042314846 | | 343.2053071078 | 1.201113639068 | | 344.2120066199 | -8.967554297055 | | 344.5092848207 | -3.76968999454 | | 345.0369565289 | -12.80783236183 | | 346.7423345683 | -9.286127524436 | | 347.1867614296 | -12.63952485965 | | 349.7190055484 | -10.25928200595 | We thank Christoph Ries from the Wendelstein Observatory staff for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42674. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40737] Fermi GRB 251113A: Global MASTER-Net observations report
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42673 SUBJECT: Fermi GRB 251113A: Global MASTER-Net observations report DATE: 25/11/13 18:46:05 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 251113A ( Fermi GBM team, GCN 42671) errorbox 3189 sec after notice time and 3223 sec after trigger time at 2025-11-13 18:31:13 UT, with upper limit up to 18.9 mag. Observations started at twilight. The observations began at zenith distance = 73 deg. The sun altitude is -15.3 deg. The galactic latitude b = -35 deg., longitude l = 179 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3041542 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3254 | 2025-11-13 18:31:13 | MASTER-SAAO | (03h 38m 31.68s , +07d 50m 32.6s) | C | 60 | 18.0 | 3314 | 2025-11-13 18:31:13 | MASTER-SAAO | (03h 38m 31.68s , +07d 50m 32.6s) | C | 180 | 18.8 | Coadd 3254 | 2025-11-13 18:31:13 | MASTER-SAAO | (03h 36m 49.82s , +08d 06m 25.7s) | C | 60 | 17.6 | 3345 | 2025-11-13 18:32:45 | MASTER-SAAO | (03h 38m 31.92s , +07d 48m 57.6s) | C | 60 | 18.2 | 3345 | 2025-11-13 18:32:45 | MASTER-SAAO | (03h 36m 50.05s , +08d 04m 49.4s) | C | 60 | 17.7 | 3438 | 2025-11-13 18:34:17 | MASTER-SAAO | (03h 38m 35.46s , +07d 50m 09.7s) | C | 60 | 18.2 | 3438 | 2025-11-13 18:34:18 | MASTER-SAAO | (03h 36m 53.59s , +08d 06m 00.6s) | C | 60 | 17.8 | 3560 | 2025-11-13 18:35:50 | MASTER-SAAO | (03h 38m 30.08s , +07d 49m 40.0s) | C | 120 | 18.8 | 3560 | 2025-11-13 18:35:50 | MASTER-SAAO | (03h 36m 48.15s , +08d 05m 30.5s) | C | 120 | 18.2 | 3713 | 2025-11-13 18:38:23 | MASTER-SAAO | (03h 38m 29.14s , +07d 50m 41.1s) | C | 120 | 18.9 | 3713 | 2025-11-13 18:38:23 | MASTER-SAAO | (03h 36m 47.11s , +08d 06m 30.9s) | C | 120 | 18.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42673. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40736] GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42672 SUBJECT: GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734) DATE: 25/11/13 18:19:45 GMT FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de> T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 784748255 at 17:37:30 on 13 Nov. 2025 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position is: RA(2000.0) = 52.6 deg Decl.(2000.0) = 10.4 deg The 1 sigma statistical error radius is 1.6 deg. We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB251113734/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB251113734/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB251113734/json View this GCN Circular online at https://gcn.nasa.gov/circulars/42672. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40735] GRB 251113A: Fermi GBM Final Real-time Localization
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42671 SUBJECT: GRB 251113A: Fermi GBM Final Real-time Localization DATE: 25/11/13 17:48:06 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 17:37:30 UT on 13 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251113A (trigger 784748255.384296 / 251113734). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 55.1, Dec = 8.2 (J2000 degrees, equivalent to J2000 03h 40m, 8d 11'), with a statistical uncertainty of 1.5 degrees. The angle from the Fermi LAT boresight is 52.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251113734/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251113734/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251113734/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42671. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40734] GRB 251111A: SVOM/ECLAIRs refined analysis
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42670 SUBJECT: GRB 251111A: SVOM/ECLAIRs refined analysis DATE: 25/11/13 15:34:26 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> H. Yang, M. Brunet, O. Godet (IRAP), W.-J. Xie (NAOC), S. Schanne, B. Hubert (CEA), Y.-H. Cheng (SWIFAR,YNU), B.-T. Wang (YNAO) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 251111A (SVOM burst-id sb25111101, GCN 42637) detected at T0 = 2025-11-11T05:10:18.26. The burst that triggered ECLAIRs consists of a single peak mostly seen in the 4-30 keV, with a duration of T90 = 5.31 (-0.68 / +2.36) s in the 4-20 keV energy band. The time-averaged spectrum from the peak (T0-5.3 s to T0+5 s) in the 5-30 keV energy range is well fitted by a power-law model with a photon index of 2.4 +/-0.2.The large photon index suggests that the peak energy is below 4 keV, indicating that this event is an X-ray flash. A blackbody model is also tested but does not provide a good fit. With the power-law model, the total 4-120 keV fluence is (1.5+/-0.2)e-07 erg/cm^2. All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Hui Yang (IRAP) (hui.yang(a)irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/42670. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40733] GRB 251025B: SVOM/ECLAIRs refined analysis
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42669 SUBJECT: GRB 251025B: SVOM/ECLAIRs refined analysis DATE: 25/11/13 14:50:40 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet (IRAP), F. Lacreu (IAP), F. Daigne (IAP), O. Godet (IRAP), S. Hussein (IJCLab) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 251025B (SVOM burst-id sb25102502, GCN 42347) detected at T0 = 2025-10-25T14:24:05. The burst that triggered ECLAIRs consists of a multiple peak lightcurve, lasting about 80 s in the 4-120 keV energy band. The time-averaged spectrum from T0-21 s to T0+39 s in the 5-120 keV energy range is best fitted by a power-law model with a photon index of 1.60 +/-0.06. With this model, the total 4-120 keV fluence is (1.52 +0.06/-0.11)e-06 erg/cm^2. All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Marius Brunet (IRAP) (marius.brunet at irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/42669. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40732] Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42668 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB DATE: 25/11/13 14:29:46 GMT FROM: Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi(a)ba.infn.it> E. Bissaldi (Politecnico and INFN Bari) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 784717756 / 251113381 at 09:09:11.19 UT on 13 November 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to a solar flare." View this GCN Circular online at https://gcn.nasa.gov/circulars/42668. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40731] GRB 251112A: Swift/UVOT Upper Limits
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42667 SUBJECT: GRB 251112A: Swift/UVOT Upper Limits DATE: 25/11/13 14:23:39 GMT FROM: Alice Breeveld at MSSL-UCL <a.breeveld(a)ucl.ac.uk> A.A. Breeveld (UCL-MSSL) and A. Mei (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251112A 304 s after the BAT trigger (Mei et al., GCN Circ. 42656). No optical afterglow consistent with the XRT position (Lanava et al., GCN Circ. 42665) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u_FC 304 553 246 >19.9 white 856 944 86 >20.0 uvw1 683 697 14 >17.2 uvm2 658 849 39 >17.6 uvw2 609 801 39 >18.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.158 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42667. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40730] LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42666 SUBJECT: LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq DATE: 25/11/13 12:12:23 GMT FROM: James Gillanders at University of Oxford <jhgillanders.astro(a)gmail.com> J. H. Gillanders (Oxford), S. J. Smartt, K. W. Smith (Oxford/QUB), S. Srivastav, H. Stevance, F. Stoppa, A. Cooper (Oxford), M. Nicholl, D. R. Young, C. R. Angus, M. D. Fulton, T. Moore, A. Aamer, M. McCollum, S. Sim, J. Weston, X. Sheng, D. Magill, P. Ramsden (QUB), L. Shingles (GSI/QUB), L. Rhodes (TSI/McGill), L. Denneau, J. Tonry, H. Weiland, R. Siverd (IfA, University of Hawaii), N. Erasmus, W. Koorts (South African Astronomical Observatory), A. Rest (STScI), T.-W. Chen (NCU), C. Stubbs (Harvard), J. Sommer (LMU/QUB), B. Schmidt (ANU): We are currently observing the skymap of the LIGO/Virgo/KAGRA GW event S251112cm (LVK Collaboration, GCN 42650) with ATLAS (Tonry et al., 2018, PASP, 13, 164505; Licandro et al., 2023, arXiv:2302.07954). ATLAS is a quintuple 0.5-m optical telescope survey system (Hawaii x2, South Africa, Chile, Tenerife) employing three filters, cyan, orange and ‘clear’. In our primary NASA mission for Near-Earth Object discovery, we cover the entire visible night sky every 24 hours to a magnitude depth of m ~ 19.5, weather and Moon permitting. We will report our candidate discoveries in an upcoming GCN. Groot et al. (GCN 42663) report on BlackGEM/MeerLICHT observations of the GW skymap of S251112cm (GCN 42650), and they present two candidate counterparts: AT2025adgp and AT2025adgq. Here, we note that both AT2025adgp and AT2025adgq have historical detections in ATLAS, which precede the GW detection. The public ATLAS data (for these and any other transient) are accessible through the ATLAS Forced Photometry Server (Shingles et al. AstroNote #2021-7). More specifically: AT2025adgp was first detected on MJD 60991.136 (~0.5 days pre-GW) in the c-band with magnitude, m_c = 19.22 +/- 0.25 (AB) mag. AT2025adgq was first detected on MJD 60988.111 (~3.5 days pre-GW) in the o-band with magnitude, m_o = 19.03 +/- 0.18 (AB) mag. Given these pre-detections, we expect that both AT2025adgp and AT2025adgq are young, rising supernovae, unrelated to the GW signal, S251112cm. However, the exact nature of the optical counterpart to a sub-solar-mass compact object merger event is uncertain, and so we cannot rule out that these transient phenomena are related in some way. Further monitoring of these candidate events will occur with ATLAS. The Asteroid Terrestrial-impact Last Alert System (ATLAS) project is primarily funded to search for Near-Earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, University of Oxford, the Queen's University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile. View this GCN Circular online at https://gcn.nasa.gov/circulars/42666. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40729] GRB 251112A: Swift-XRT refined Analysis
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42665 SUBJECT: GRB 251112A: Swift-XRT refined Analysis DATE: 25/11/13 10:27:12 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: We have analysed 847 s of XRT data for GRB 251112A, from 90 s to 939 s after the Swift trigger. The data comprise 64 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The refined XRT position is RA, Dec = 274.0697, +24.1535 which is equivalent to: RA (J2000): 18h 16m 16.72s Dec(J2000): +24d 09' 12.5" with an uncertainty of 4.1 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=3.14 (+0.34, -0.30). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 3.3 (+/-0.4). The best-fitting absorption column is 4.9 (+1.3, -1.1) x 10^21 cm^-2, in excess of the Galactic value of 1.8 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 2.2 x 10^-11 (1.1 x 10^-10) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 4.9 (+1.3, -1.1) x 10^21 cm^-2 Galactic foreground: 1.8 x 10^21 cm^-2 Excess significance: 4.6 sigma Photon index: 3.3 (+/-0.4) If the light curve continues to decay with a power-law decay index of 3.14, the count rate at T+24 hours will be 7.8 x 10^-9 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x 10^-19 (8.4 x 10^-19) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01413695. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42665. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40728] GRB 251108C: AstroSat CZTI detection
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42664 SUBJECT: GRB 251108C: AstroSat CZTI detection DATE: 25/11/13 09:10:52 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), A. Goyal (IITB), A. Arya (IITB), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 251108C. This burst was also detected by the Konus-Wind team (priv. comm.) T0(KW) = 23:08:03.415 UT. The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-11-08 23:07:57.38 UTC. The measured peak count rate associated with the burst is 250 (+36, -38) counts/s above the background in the combined data of all quadrants, with a total of 630 (+121, -124) counts. We caution that there is a 0.3 s readout dead time in CZT data during the burst which affects the calculated total counts. The local mean background count rate was 257 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 7.0 (+1.8, -1.6) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-08 23:07:56.96 UTC The measured peak count rate associated with the burst is 660 (+49, -53) counts/s above the background in the combined data of all quadrants, with a total of 3568 (+326, -374) counts. The local mean background count rate was 1128 (+7, -7) counts/s. Using cumulative rates, we measure a T90 of 10.9 (+3.2, -3.0) s. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42664. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40727] LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42663 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq DATE: 25/11/13 08:46:10 GMT FROM: Paul Groot at Radboud University Nijmegen <p.groot(a)astro.ru.nl> P.J. Groot (Radboud/UCT/SAAO) , H. Tranin (Barcelona), J. van Roestel (ISTA), P.M. Vreeswijk (Radboud), D. Pieterse (Radboud), G. Leloudas (DTU Space), N. Blagorodnova (Barcelona), S. Bloemen (Radboud), G. Ramsay (Armagh), S. Scaringi (Durham) report on behalf of the BlackGEM and MeerLICHT consortia: "The BlackGEM and MeerLICHT telescopes (Groot et al., 2024) reacted to the LVK-announced gravitational wave event S251112cm (LVK2025, GCN Circ. 42650). Both telescope systems covered about 50% of the 90% error box, primarily the part located in the Southern Hemisphere. A detailed overview of observations will be given in a subsequent report. Here we report the detection of AT2025adgp (BGEM J014746.20-514925.5), and AT2025adgq (MLT J002931.8-393051.6) as two newly detected transients in the BlackGEM/MeerLICHT footprint, which, on average, had a limiting magnitude for new transients of q~19.8. AT2025adgp is located at RA, Dec (ICRS) = 01:47:46.202 -51:49:25.52 (26.942508d, -51.823756d) with an uncertainty of 0.1" in each coordinate. It was detected on 2025-11-13 03:09:48 and 03:25:29 UT in the BlackGEM q-band (440-720 nm) filter using the BG-2 telescope, at, respectively, q=19.31+/-0.12 and q=19.29+/-0.12. The first detection was 11h50m after the LVK Trigger time. The transient is located in the southern outskirts of a face-on spiral galaxy WISExSCOS J014746.23-514922.5, listed in the Regalade catalog (Tranin et al., 2025) at a luminosity distance of D_L =246 Mpc with a large standard deviation, and in the GLADE+ (Dalya et al., 2020) catalog at D_L = 250 +/- 45 Mpc. If the galaxy is the host of AT2025adgp this would put its distance at the upper edge of consistency with the distance to S251112cm as announced by the LVK collaboration at D_S251112cm = 96 +/- 29 Mpc. AT2025adgq is located at RA,Dec (ICRS) = 00:29:31.8, -39:30:51.6 (7.38245842d, -39.5143190d) with an uncertainty of 0.1” in each coordinate. It was detected on 2025-11-13 00:03:38 and 00:04:43 UT in the BlackGEM q-band (440-720 nm) filter using the MeerLICHT telescope at, q=19.28+/-0.10 in each exposure. The first detection was 08h44m after the LVK trigger. The BlackGEM array also detected AT2025adgq on 2025-11-13 01:05:23 UT and 01:22:00 UT using the BG-2 telescope at q=19.28 +/- 0.10 and q=19.41 +/- 0.1, respectively. The transient is located in the north-eastern elongation of an oblated galaxy, WISExSCOS J002932.49-393059.7, listed in the Regalade catalog at a luminosity distance of D_L = 279 +/- 130 Mpc, and in the GLADE+ catalog at D_L = 300 +/- 68 Mpc. If the galaxy is the host of AT2025adqp this would put its distance at the upper edge of consistency with the distance to S251112cm as announced by the LVK collaboration. We encourage spectroscopic classification of AT2025adgp and AT2025adgq to confirm their nature and distance, and therefore the possibility of them being a counterpart to S251112cm." References: Groot et al., 2024, PASP 136, 5003, Tranin et al., 2025, arXiv250813267T, Dalya et al., 2020, VizieR On-line Data Catalog: VII/275; LVK2025, 2025, GCN 42650 View this GCN Circular online at https://gcn.nasa.gov/circulars/42663. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40726] GRB 251112B: MAXI/GSC detection
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42662 SUBJECT: GRB 251112B: MAXI/GSC detection DATE: 25/11/13 03:24:59 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> T. Kawamuro (Osaka U.), M. Nakajima (Nihon U.), Y. Kawakubo, M. Serino (AGU), H. Negoro, K. Takagi, H. Takahashi, H. Nishio (Nihon U.), T. Mihara, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, H. Hiramatsu, Y. Kondo, A. Yoshida (AGU), Y. Tsuboi, H. Sugai, N. Nagashima, Y. Ishihara (Chuo U.), M. Shidatsu, C. Kang, T. Nakamoto, M. Uenishi, T. Usuki, S. Yatsuzuka (Ehime U.), I. Takahashi, Y. Yatsu (Science Tokyo), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, M. Kurihara (JAXA), Y. Ueda, K. Fujiwara (Kyoto U.), M. Yamauchi, M. Nishio, C. Hiraizumi (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Sugizaki (Kanazawa U.), W. Iwakiri (Chiba U.), S. Yamada (Tohoku U) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 20:54:12 UT on November 12, 2025. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (278.962 deg, 18.196 deg) = (18 35 50, +18 11 45) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.30 deg and 0.26 deg, respectively. The roll angle of long axis from the north direction is 99.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 146 +- 34 mCrab (4.0-10.0keV, 1 sigma error). Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners: (R.A., Dec) = (277.696, 16.760) deg = (18 30 47, +16 45 36) (J2000) (R.A., Dec) = (278.212, 16.464) deg = (18 32 50, +16 27 50) (J2000) (R.A., Dec) = (279.748, 18.876) deg = (18 38 59, +18 52 33) (J2000) (R.A., Dec) = (279.227, 19.177) deg = (18 36 54, +19 10 37) (J2000) There was no significant excess flux in the previous transit at 19:21 UT and in the next transit at 22:27 UT with an upper limit of 20 mCrab for each. View this GCN Circular online at https://gcn.nasa.gov/circulars/42662. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40725] Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42661 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB DATE: 25/11/13 02:41:40 GMT FROM: Lorenzo Scotton at UAH <lscottongcn(a)outlook.com> L. Scotton (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 784687703/251113034 at 00:48:18.02 UT on 13 November 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to distant particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/42661. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40724] Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42660 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB DATE: 25/11/13 02:40:53 GMT FROM: Lorenzo Scotton at UAH <lscottongcn(a)outlook.com> L. Scotton (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 784687099/251113027 at 00:38:14.12 UT on 13 November 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to distant particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/42660. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40723] LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42659 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations DATE: 25/11/13 02:29:27 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> H. Hiramatsu, S. Sugita, M. Serino, Y. Kawakubo, Y. Kondo (AGU) H. Negoro, M. Nakajima, K. Takagi (Nihon U.), N. Kawai, T. Mihara, (RIKEN), report on behalf of the MAXI team: We examined MAXI/GSC all-sky X-ray images (2-20 keV) after compact binary merger candidate S251112cm at 2025-11-12 15:18:45.362 UTC (GCN #42650). At the trigger time of S251112cm, the high-voltage of MAXI/GSC was on. The instantaneous field of view of GSC at the GW trigger time covered 1% of the 90% credible region of the bayestar sky map, in which we found no significant new X-ray source. The first one-orbit (92 min) scan observation with GSC after the event covered 72% of the 90% credible region of the bayestar skymap from 15:18:45 to 16:50:09 UTC (T0+0 to T0+5484 sec). No significant new source was found in the region in the one-orbit scan observation. A typical 1-sigma averaged upper limit obtained in one scan observation is 20 mCrab at 2-20 keV. If you require information about X-ray flux by MAXI/GSC at specific coordinates, please contact the submitter of this circular by email. View this GCN Circular online at https://gcn.nasa.gov/circulars/42659. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40722] LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42658 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations DATE: 25/11/12 22:47:23 GMT FROM: kendall.ackley(a)warwick.ac.uk K. Ackley, B. Godson, D. O'Neill, B. P. Gompertz, M. Dyer, J. Lyman, K. Ulaczyk, S. Belkin, T. Killestein, A. Kumar, M. Pursiainen, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. P. Breton, J. Casares Velásquez, L. K. Nuttall, report on behalf of the GOTO collaboration: We carried out optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al 2024) in response to the LIGO/Virgo/KAGRA gravitational wave candidate event S251112cm (GCN 42650). Targeted observations were performed by GOTO-South (Siding Spring, Australia) starting at 2025-11-12 16:09:51 UT, (+0.85h post trigger) and continued through to 2025-11-12 17:51:21 UT (+2.54h post trigger). A total of 39 image sets with exposures of 4x60s and 4x90s were taken across 6 unique pointings, covering 250.5 sq. degrees within the 90% localisation contour of the initial skymap. We covered approximately 14.6% of the total 2D localisation probability with an average 5-sigma depth of L~19.9 mag (AB). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogs. Human vetting was carried out in real time on any candidates that passed the above checks. Within the initial skymap, we identify 2 optical sources within the 90% contour and 1 optical source within the 99% probability contour. We find no convincing evidence of excess flux in either GOTO25jyg/AT2025addc or GOTO25jya/AT2025adcv prior to the GW trigger time in previous GOTO observations or the ZTF observations provided by the Lasair broker (Smith et al. 2019). The ATLAS forced photometry server (Shingles et al. 2021) returns recent detections for GOTO25jyg and GOTO25jya, albeit at low significance. We encourage further analysis to confirm these pre-detections. We note that GOTO25jya appears to be associated with a GLADE+ galaxy HyperLEDA 422311 with zphot~0.01 (D_L~474 Mpc) which, if correct, would put it outside the nominal luminosity distance estimates of S251112cm. We do not find a host galaxy underlying GOTO25jyg. There is a galaxy located 9.27 arcsec from the candidate’s position within the Legacy DR10 photometric redshift catalog with zphot ~ 0.3 (Dey et al. 2019). GOTO25jye/AT2025adcy is located outside of the 90% probability contour of the initial skymap and is potentially associated with a GLADE+ galaxy HyperLEDA 389528 at zphot ~ 0.13 (D_L~664 Mpc). This association would make this candidate unlikely to be related to S251112cm. | Internal name | IAU name | RA(J2000) | Dec(J2000) | Mag(AB) | | ------------- | ---------- | ----------- | ------------ |--------------- | | GOTO25jyg | AT2025addc | 04:55:26.13 | -53:09:43.61 | 19.93 +/- 0.20 | | GOTO25jya | AT2025adcv | 03:05:58.60 | -54:09:06.60 | 19.30 +/- 0.10 | | GOTO25jye | AT2025adcy | 04:35:28.56 | -57:28:31.64 | 19.71 +/- 0.12 | Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and not corrected for Galactic extinction. Continued observations are planned from both GOTO sites, weather permitting. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester, the University of Birmingham and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/42658. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40721] GRB 251108B: Glowbug gamma-ray detection
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42657 SUBJECT: GRB 251108B: Glowbug gamma-ray detection DATE: 25/11/12 22:29:39 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251108B, which was also detected by Konus-Wind (Trig_Time = 03:59:31.499 UT). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-11-08 03:59:18.952 with a duration of 15.4 s and a total significance of about 40 sigma. The light curve comprises two primary peaks at ~T0+7s and T0+13s. Note that data from ~T0-1s to T0+3s suffered from deadtime in various detectors. The best-fit localization is RA, Decl. (J2000, deg) = 283.3, 48.0 with a radius of 7.8 deg (95% confidence), with a highly uncertain systematic uncertainty. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42657. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40720] Swift Trigger 1413695: a possible GRB 251112A
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42656 SUBJECT: Swift Trigger 1413695: a possible GRB 251112A DATE: 25/11/12 22:04:25 GMT FROM: James DeLaunay at PSU <jjd330(a)psu.edu> A. Mei (INAF-OAB), J. J. DeLaunay (PSU), M. Ferro (INAF-OAB), R. Gupta (NASA GSFC) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 21:28:56 UT, the Swift Burst Alert Telescope (BAT) triggered and located a possible GRB 251112A (trigger=1413695). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 274.019, +24.226 which is RA(J2000) = 18h 16m 05s Dec(J2000) = 24d 13' 32" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 60 sec. The peak count rate was ~600 counts/sec (15-350 keV), at ~25 sec after the trigger. The XRT began observing the field at 21:30:22.7 UT, 86.9 seconds after the BAT trigger. No source was detected in 782 s of promptly downlinked data. We are waiting for the full dataset to detect and localise the XRT counterpart. UVOT took a finding chart exposure of 150 seconds with the White filter starting 91 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.161. Due to no credible afterglow candidate in the initial XRT and UVOT data, we for now call this a possible GRB while we wait for additional data for further inspection. Burst Advocate for this burst is A. Mei (alessio.mei AT inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42656. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40719] LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42655 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations DATE: 25/11/12 21:37:57 GMT FROM: Angus Jameson <abj0023(a)uah.edu> S. Bala (USRA) & A. Jameson (UAH) reports on behalf of the Fermi-GBM Team: For S251112cm (GCN 42650) and using the initial/updated bayestar/Bilby skymap, Fermi-GBM was observing 68.6% of the localization probability at event time. There was a Fermi-GBM onboard trigger 784653403/251112637, around two mins before the event time of the LIGO/Virgo/KAGRA (LVK) detection of GW S251112cm, due to local particles (GCN 42652). An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterpart candidates. The GBM targeted search, the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around merger time, and also identified no counterpart candidates. Part of the LVK localization region is behind the Earth for Fermi, located at an RA=4.4, Dec=25.2 with a radius of 68 degrees. We therefore set upper limits on impulsive gamma-ray emission for the GW localization region visible to Fermi at merger time. Using the representative soft, normal, and hard GRB-like templates described in arXiv:1612.02395, we set the following 3 sigma flux upper limits over 10-1000 keV, weighted by GW localization probability (in units of 10^-7 erg/s/cm^2): Timescale Soft Normal Hard (Please put these in the appropriate units for 10^-7 erg/s/cm^2) ------------------------------------ 0.128 s: 4.1 6.1 7.7 1.024 s: 2.0 2.7 3.4 8.192 s: 1.0 1.4 1.3 Assuming the median luminosity distance of 96 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^47 erg/s): Timescale Soft Normal Hard ------------------------------------ 0.128s: 6.9 9.6 19.8 1.024s: 3.3 4.2 8.7 8.192s: 1.7 2.2 3.3 View this GCN Circular online at https://gcn.nasa.gov/circulars/42655. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40718] Fermi trigger No 784621743: Global MASTER-Net observations report
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42654 SUBJECT: Fermi trigger No 784621743: Global MASTER-Net observations report DATE: 25/11/12 18:31:42 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB251112.27 (trigger No 784621743,23h 29m 40.01s , -30d 28m 00.1s, R=29.9667) errorbox 39751 sec after notice time and 39794 sec after trigger time at 2025-11-12 17:32:13 UT, with upper limit up to 17.2 mag. The observations began at zenith distance = 79 deg. The sun altitude is -40.6 deg. The galactic latitude b = -72 deg., longitude l = 18 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3040029 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 39824 | 2025-11-12 17:32:13 | MASTER-Kislovodsk | (22h 51m 27.41s , -34d 46m 00.2s) | C | 60 | 17.1 | 40126 | 2025-11-12 17:37:15 | MASTER-Kislovodsk | (23h 09m 59.14s , -34d 43m 09.6s) | C | 60 | 17.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42654. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40717] LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42653 SUBJECT: LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume DATE: 25/11/12 17:00:07 GMT FROM: David Cook at Caltech/IPAC-NED <dcook(a)ipac.caltech.edu> David O. Cook (Caltech/IPAC), Rick Ebert (Caltech/IPAC), George Helou (Caltech/IPAC), Joseph M. Mazzarella (Caltech/IPAC), Marion Schmitz (Caltech/IPAC), and Leo Singer (NASA/GSFC) On behalf of the NASA/IPAC Extragalactic Database (NED) Team. We spatially cross-matched the LVK S251112cm-3-Initial sky localization with the NED Local Volume Sample (NED-LVS; Cook et al. 2023; https://ned.ipac.caltech.edu/NED::LVS/) which is a subset of NED with a redshift or redshift-independent distance less than 1000 Mpc. We find 7731 galaxies within the 90% containment volume, and we list here the top 20 galaxies sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full or top 20 list of galaxies in the 90% volume go either to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/ or click on the following links: Full List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S251112cm/3 Top 20 List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S251112cm/3/20 The NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic follow-up observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D * P_SFR; and specific star formation rate, P_3D * P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume. | objname| ra| dec|objtype| DistMpc|DistMpc_unc| m_NUV| m_NUV_unc| m_Ks| m_Ks_unc| m_W1| m_W1_unc| P_3D|P_3D_LumW1| |-------------------------|--------------|--------------|-------|-----------|-----------|------------|------------|------------|------------|------------|------------|--------|----------| | NGC 2960| 145.15161| 3.57703| G| 76.97| 7.94| 17.522| 0.003| 9.783| 0.038| 9.672| 0.002|1.71e-05| 1.08e-08| | IC 1471| 347.18676| -12.63948| G| 83.00| 17.58| 17.246| 0.027| 10.334| 0.035| 10.290| 0.006|1.79e-05| 7.44e-09| | NGC 7396| 343.09426| 1.09241| G| 81.16| 8.50| 17.854| 0.004| 8.699| 0.022| 8.557| 0.012|3.66e-06| 7.25e-09| | UGC 05226| 146.51479| 4.40348| G| 66.86| 15.78| 18.763| 0.092| 10.211| 0.041| 10.083| 0.089|2.17e-05| 7.08e-09| | IC 0564| 146.58792| 3.07130| G| 75.75| 2.62| null| null| 10.033| 0.035| 10.010| 0.006|1.51e-05| 6.79e-09| | NGC 3070| 149.52893| 10.35980| G| 60.25| 5.89| 18.225| 0.068| 9.260| 0.030| 9.503| 0.006|1.45e-05| 6.56e-09| | IC 1464B| 345.79587| -8.98909| G| 105.88| 0.59| null| null| 10.015| 0.036| 9.741| 0.006|5.69e-06| 6.38e-09| |WISEA J100012.04+093856.0| 150.05020| 9.64890| G| 78.82| 0.30| null| null| 11.073| 0.096| 10.233| 0.006|1.53e-05| 6.05e-09| | UGCA 150| 137.70611| -8.89069| G| 28.38| 0.82| null| null| 7.704| 0.006| 7.044| 0.041|5.28e-06| 5.11e-09| | IC 1633| 17.48145| -45.93116| G| 96.06| 3.43| null| null| 8.396| 0.025| 8.999| 0.006|2.80e-06| 5.10e-09| | NGC 3540| 167.31704| 36.02108| G| 93.24| 0.04| 19.626| 0.150| 10.168| 0.041| 10.319| 0.006|9.87e-06| 5.03e-09| | NGC 2987| 146.42281| 4.94189| G| 54.46| 0.58| 17.338| 0.002| 10.146| 0.048| 9.912| 0.006|1.97e-05| 4.99e-09| | NGC 7646| 351.02906| -11.86050| G| 79.59| 2.73| 16.328| 0.004| 10.358| 0.037| 8.371| 0.005|2.21e-06| 4.94e-09| | MCG -01-24-010| 140.09147| -7.88074| G| 53.94| 2.54| 15.885| 0.007| 10.054| 0.032| 9.821| 0.030|1.78e-05| 4.81e-09| | ESO 197- G 021| 31.13585| -52.17213| G| 87.54| 0.39| null| null| 9.099| 0.026| 9.375| 0.006|4.26e-06| 4.56e-09| | NGC 4187| 183.37201| 50.74150| G| 120.62| 5.52| 18.691| 0.027| 9.772| 0.027| 9.930| 0.006|3.73e-06| 4.56e-09| | UGC 05267| 147.47044| 9.09562| G| 80.08| 3.03| null| null| 10.147| 0.042| 10.208| 0.006|1.08e-05| 4.52e-09| | NGC 7364| 341.10153| -0.16213| G| 76.48| 8.25| 16.366| 0.001| 9.478| 0.028| 9.218| 0.003|4.69e-06| 4.46e-09| | NGC 0010| 2.14394| -33.85835| G| 87.84| 3.70| null| null| 9.205| 0.042| 9.975| 0.006|7.18e-06| 4.45e-09| | UGC 05855| 161.15400| 26.18153| G| 91.46| 2.06| 17.681| 0.037| 10.212| 0.028| 10.184| 0.006|7.99e-06| 4.45e-09| Table 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S251112cm sorted by the joint probability of 3D position and WISE W1 luminosity (P_3D * P_LumW1). Galaxy is the NED preferred name. RA and Dec are the Equatorial coordinates in degrees (J2000). Objtype is the object type of the galaxy candidate. Distance is the distance to the galaxy in Mpc. m_NUV and mErr_NUV are the apparent magnitude and error from GALEX. m_Ks and mErr_Ks are the apparent magnitude and error from 2MASS. m_W1 and mErr_W1 are the apparent magnitude and error from AllWISE. P_3D is the probability that the galaxy is in the volume given the distance of GW event. P_3D_LumW1 is the joint probability within the volume weighted by the WISE1 luminosity of the galaxy (P_3D * P_LumW1). View this GCN Circular online at https://gcn.nasa.gov/circulars/42653. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40716] Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42652 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB DATE: 25/11/12 16:53:58 GMT FROM: Angus Jameson <abj0023(a)uah.edu> A. Jameson (UAH) & S. Bala (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 784653403/251112637 at 15:16:38.19 UT on 12 November 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to Local Particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/42652. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40715] GRB251111A: 1.3m DFOT optical upper limit
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42651 SUBJECT: GRB251111A: 1.3m DFOT optical upper limit DATE: 25/11/12 16:45:38 GMT FROM: ANSHIKA GUPTA at ARIES <anshika05180(a)gmail.com> Anshika Gupta, Kumar Pranshu, Debolina Kar, Dhruv Jain, Pankaj Pawar and Kuntal Misra (ARIES) report: We observed the field of GRB251111A detected by SVOM (Cheng et al. 2025, GCN 42637), with the 1.3m Devasthal Fast Optical Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2025-11-11 at 15:37:41 UT, i.e., ~10.45 hours after the SVOM trigger. We have taken multiple frames with an exposure time of 300 s in the R filter. We stacked the images after the alignment. We could not detect the optical emission in our stacked image within the error box of SVOM/COLIBRÍ (López-Cámara et al. 2025, GCN 42638) & Swift-XRT (Campana et al. 2025, GCN 42648). We obtain the following 3-sigma upper limit in the stacked image: Date Start_UT T_start-T0 (hour) Filter Exp time (s) Magnitude =============================================================== 2025-11-11 15:37:41 ~10.45 R 300s*24 >23.2 The upper limit of the burst is consistent with López-Cámara et al. 2025 (GCN 42638); Wu et al. 2025 (GCN 42639); Zheng et al. 2025 (GCN 42640); Wu et al. 2025 (GCN 42641); Ma et al. 2025 (GCN 42647). The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalogue. View this GCN Circular online at https://gcn.nasa.gov/circulars/42651. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40714] LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42650 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate DATE: 25/11/12 15:55:25 GMT FROM: Alicia Calafat <alicia.calafat(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251112cm during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-11-12 15:18:45.362 UTC (GPS time: 1446995943.362). The candidate was found by the MBTA SSM [1] analysis pipeline. S251112cm is an event of interest because its false alarm rate, as estimated by the online analysis, is 5.1e-09 Hz, or about one in 6 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251112cm The analysis which found this candidate used a template bank including sub-solar-mass components. The usual classification probabilities for BNS, NSBH, or BBH binaries versus Terrestrial noise are not calculated for this candidate. The probability of matter remaining outside the final compact object (HasRemnant) [2] is not estimated either. Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass between 1 and 3 solar masses (HasNS) is 8%. [2] The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The probability that the lighter compact object is below 1 solar mass (HasSSM) is >99%. The source chirp mass falls with highest probability in the bin (0.1, 0.87) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [3], distributed via GCN and SCiMMA notices about 57 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [3], distributed via GCN and SCiMMA notices about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 1220 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 96 +/- 29 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [2] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [3] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42650. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40713] GRB 251106B: Glowbug gamma-ray detection of a likely short burst
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42649 SUBJECT: GRB 251106B: Glowbug gamma-ray detection of a likely short burst DATE: 25/11/12 15:46:47 GMT FROM: richard.s.woolf.civ(a)us.navy.mil R. Woolf, C.C. Cheung, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251106B, which was also detected by SVOM/GRM (GCN 42612) and Insight-HXMT/HE (GCN 42633). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-11-06 18:14:42.936 with a duration of 1.02 s and a total significance of about 7.3 sigma. The light curve comprises two primary peaks within 1-s duration. Note that data from ~T0 to T0+2.2s and ~T0+3s to T0+5.2s suffered from deadtime in various detectors. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42649. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40712] GRB 251111A: Swift-XRT afterglow detection
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42648 SUBJECT: GRB 251111A: Swift-XRT afterglow detection DATE: 25/11/12 10:51:12 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Campana (INAF-OAB), D.N. Burrows (PSU), S. Lanava (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of GRB 251111A. We searched for X-ray sources in 2.1 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 2.1 ks, obtained between T0+7.6 ks and T0+36.9 ks. An uncatalogued X-ray source is detected and is believed to be the afterglow. Using 305 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 32.36166, +5.22815 which is equivalent to: RA (J2000): 02h 09m 26.80s Dec(J2000): +05d 13' 41.3" with an uncertainty of 5.1 arcsec (radius, 90% confidence). The observed count rate was 2.5 (+1.2, -0.9)e-02 count/s at T0+7.7 ks, falling to 5.2 (+2.6, -1.9)e-03 at T0+33.8 ks, which indicates the X-ray source is fading. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/03000189. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00049. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42648. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40711] GRB 251111A: SVOM/VT optical observations with X-band data
by GCN Circulars 12 Nov '25

12 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42647 SUBJECT: GRB 251111A: SVOM/VT optical observations with X-band data DATE: 25/11/12 07:32:30 GMT FROM: Yinuo Ma <mayn(a)bao.ac.cn> Y. N. Ma, H. L. Li, L. P. Xin, Z. H. Yao, Y. L. Qiu, C. Wu, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), Y. H. Cheng (SWIFAR, YNU), B. T. Wang(YNAO) report on behalf of the SVOM/VT team. SVOM/VT performed an automatic slew on the burst GRB 251111A (sb25111101) triggered by SVOM/ECLAIRs (Cheng et al., GCN 42637). SVOM/VT began observing the field at 2025-11-11 06:01:57 UTC, 51.656 minutes after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. With X-band data available, the optical counterpart (López-Cámara et al., GCN 42638; Wu et al., GCN 42639; Zheng et al., GCN 42640; Wu et al., GCN 42641) was detected in VT_R band within XRT's error box (Evans et al., GCN 42645) and EP-FXT's error box (Cheng et al., GCN 42643) at the mid time of 1.34 hour, followed with a decay slope of -0.7. The measurements are: mid time (h) | exposure time (s) | band | mag (AB) -------------|-------------------|------|---------------- 1.34 | 28*50 | VT_R | 22.3+/-0.2 6.10 | 14*100 | VT_R | 23.5+/-0.3 Data analysis is on going. Our photometry was not corrected for Galactic extinction. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/42647. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40710] SVOM GRB251111.42: Global MASTER-Net observations report
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42646 SUBJECT: SVOM GRB251111.42: Global MASTER-Net observations report DATE: 25/11/11 15:28:29 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the SVOM GRB251111.42 (trigger No 1762855221,21h 58m 08.11s , -32d 32m 58.9s, R=1) errorbox 17209 sec after notice time and 17236 sec after trigger time at 2025-11-11 14:47:37 UT, with upper limit up to 16.2 mag. Observations started at twilight. The observations began at zenith distance = 76 deg. The sun altitude is -10.6 deg. The galactic latitude b = -53 deg., longitude l = 14 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3038591 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 17327 | 2025-11-11 14:47:37 | MASTER-Kislovodsk | (21h 55m 21.98s , -32d 13m 40.7s) | C | 180 | 15.8 | 17327 | 2025-11-11 14:47:37 | MASTER-Kislovodsk | (22h 00m 17.67s , -32d 36m 56.7s) | C | 180 | 16.2 | 17468 | 2025-11-11 14:50:58 | MASTER-Kislovodsk | (22h 00m 08.74s , -32d 41m 52.6s) | C | 60 | 15.6 | 17468 | 2025-11-11 14:50:58 | MASTER-Kislovodsk | (22h 05m 05.54s , -33d 05m 13.1s) | C | 60 | 16.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42646. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40709] GRB 251111A: Swift-XRT observations
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42645 SUBJECT: GRB 251111A: Swift-XRT observations DATE: 25/11/11 14:02:01 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi (INAF-IASFPA) , A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), M. Ferro (INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected source GRB 251111A, collecting 288 s of Photon Counting (PC) mode data between T0+7.4 ks and T0+7.8 ks after the trigger. We have detected 1 source. This has been automatically classified as an uncatalogued X-ray source. Uncatalogued X-ray sources -------------------------- Source 1 (SWIFT J020926.8+051342): ================================== RA (J2000.0): 32.3618 = 02 09 26.83 Dec (J2000.0): +5.2284 = +05 13 42.2 Error: 5.7 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 2.0 arcmin from the SVOM/ECLAIRs position. Mean rate: 0.0264 [+0.0127, -0.0096] ct s^-1 Mean flux: (7.2 [+3.5, -2.6])e-13 erg cm^-2 s^-1 Peak rate: 0.0264 [+0.0127, -0.0096] ct s^-1 Peak flux: (7.2 [+3.5, -2.6])e-13 erg cm^-2 s^-1 ECF: 2.73e-11 erg cm^-2 ct^-1 assuming NH=5.07e+20 cm^-2, gamma=2.63 determined from a spectral fit. XMM UL: 2.6e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. The XRT position is consistent the optical counterpart reported by the SVOM/COLIBRÍ (FM-GFT; López-Cámara et al., GCN Circ. 42638), LCO 1m (Wu et al., GCN Circ. 42639) and SVOM/VT (Wu et al., GCN 42641) telescopes, as well as the Einstein Probe FXT X-ray detection (Cheng et al. 42643). All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00049. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42645. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40708] SVOM GRB251111.22: Global MASTER-Net observations report
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42644 SUBJECT: SVOM GRB251111.22: Global MASTER-Net observations report DATE: 25/11/11 13:28:25 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the SVOM GRB251111.22 (trigger No 1762837816,02h 09m 30.79s , +05d 15m 24.1s, R=0.1259) errorbox 28018 sec after notice time and 28619 sec after trigger time at 2025-11-11 13:07:15 UT, with upper limit up to 19.9 mag. The observations began at zenith distance = 58 deg. The sun altitude is -34.8 deg. The galactic latitude b = -52 deg., longitude l = 157 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3038098 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 28650 | 2025-11-11 13:07:15 | MASTER- | (02h 09m 32.85s , +04d 36m 16.3s) | C | 60 | 19.8 | 28650 | 2025-11-11 13:07:15 | MASTER-Tunka | (02h 09m 14.02s , +04d 42m 25.1s) | C | 60 | 19.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42644. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40707] GRB 251111A: EP-FXT counterpart detection
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42643 SUBJECT: GRB 251111A: EP-FXT counterpart detection DATE: 25/11/11 13:12:22 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.H. Cheng (SWIFAR,YNU), Z. M. Wang (BNU), Y. J. Zhang (THU), C. L. Guo, J. W. Hu, Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 251111A (SVOM/sb25111101, Cheng et al., GCN #42637) at 2025-11-11 06:06:55 (UTC), about 0.93 hours after the SVOM/ECLAIRs trigger, with an exposure time of 1939 s. One uncatalogued source is detected within the ECLAIRs error circle, and the source is spatially consistent with the counterpart reported in optical band (López-Cámara et al., GCN #42638; Wu et al., GCN #42639, Zheng et al., GCN #42640, Wu et al., GCN #42641). Preliminary analysis on this source is automatically conducted, and the details are listed as follows. Source 1 ：EPF_J020926.9+051342 RA (J2000): 32.362 Dec (J2000): 5.228 Flux: 1.24 x 10^-12 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 3.53 x 10^-13 erg/s/cm2 (1 sigma) The position uncertainty of the source is about 10 arcsec in radius (90% C.L. statistical and systematic). Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42643. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40706] GRB 251013C: Chandra X-ray observations and jet break detection
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42642 SUBJECT: GRB 251013C: Chandra X-ray observations and jet break detection DATE: 25/11/11 10:50:45 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo(a)ucd.ie> A. Martin-Carrillo (UCD), B. P. Gompertz (Birmingham), D. B. Malesani (DAWN/NBI and Radboud), report on behalf of a larger collaboration: We observed the afterglow of GRB 251013C (Fermi GBM team, GCN 42221; Rakotondrainibe et al., GCN 42222) with the Chandra X-ray Observatory starting on 2025-11-09 at 03:09:42 UT (i.e., T0+27.396 d, observer frame), for a total of 40 ks exposure, in response to our DDT request (PI A. Martin-Carrillo, ObsID 31983). A faint X-ray source is detected at a location consistent with that of the afterglow (Palmerio et al., GCN 42223; Laskar et al., GCN 42243). Assuming a spectrum model consistent with the one measured by Swift/XRT (Evans et al., GCN 42232; https://www.swift.ac.uk/xrt_spectra/03000137/) we infer a flux in the 0.3-10 keV energy range of ~2.5e-15 erg s^-1 cm^-2. This late Chandra observation implies that the source has undergone significant steepening in its X-ray flux decay when compared with the earlier Swift/XRT and EP/FXT observations (Evans et al., GCN 42232; Wang et al., GCN 42247), suggesting a jet break sometime between 6 and 10 days since trigger in the observer frame. We thank the entire CXO team for the rapid evaluation and scheduling of our observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42642. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40705] GRB 251111A: SVOM/VT optical observations with VHF data
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42641 SUBJECT: GRB 251111A: SVOM/VT optical observations with VHF data DATE: 25/11/11 09:01:37 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu (NAOC), J. T. Palmerio (CEA), L.P. Xin (NAOC), H.L. Li, Y. L. Qiu, Yehao Cheng (SWIFAR,YNU), Boting Wang(YNAO) report on behalf of the SVOM team. SVOM/VT performed an automatic slew on the burst of GRB 251111A (sb25111101) triggered by SVOM/ECLAIRs (Cheng et al. GCN 42637). SVOM/VT began observing the field automatically at 2025-11-11T06:01:57 UTC, 51.65 minutes after the T0, with the slew of the platform triggered on-board, in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. We confirm the detection of the source reported by López-Cámara et al. (GCN 42638) and Wu et al. (GCN 42639) in the VT_R band with the downlinked VHF data. The AB magnitude was derived as follows: -------------------------------------------- (T-T0)_mid exptime band mag 54.15 min 300 sec VT_R 21.32 +/-0.11 No correction for Galactic extinction was applied to the photometry. This result is consistent with the report by Zheng et al. (GCN 42640) The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/42641. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40704] GRB 251111A: KAIT optical upper limit
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42640 SUBJECT: GRB 251111A: KAIT optical upper limit DATE: 25/11/11 08:13:13 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, automatically responded to the SVOM GRB 251111A (Cheng et al., GCN 42637) starting at 05:12:13, 115 seconds after the burst. Observations were performed in 3 x 3 tiling mode, and a set of clear (roughly R) filter images were obtained. The first image covered the reported afterglow (López-Cámara et al., GCN 42638; Wu et al., GCN 42639) position was at 05:14:50, 272 seconds after the burst. We did not detect the afterglow in our clear images with the following upper limit: mid t-t0(s) exp(s) UL(mag) --------------------------- 282 20 >18.5 561 20 >18.5 763 20 >18.5 1042 20 >18.5 1323 20 >18.5 1690 40 >19.0 2156 40 >19.0 2613 40 >19.0 3168 60 >19.5 3813 60 >19.5 4442 60 >19.5 View this GCN Circular online at https://gcn.nasa.gov/circulars/42640. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40703] GRB 251111A: LCO optical observation
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42639 SUBJECT: GRB 251111A: LCO optical observation DATE: 25/11/11 07:59:03 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu (NAOC), L. P. Xin, Xuhui Han, J. T. Palmerio (CEA/Irfu), D. Turpin, A. Saccardi, B. Cordier report on behalf of the SVOM mission team: We observed the field of GRB 251111A (SVOM/ECLAIRs, Cheng et al. GCN 42637) with the LCO 1m telescope at Cerro Tololo Inter-American Observatory equipped with the Sinistro instrument. Our observation started at 2025-11-11T05:31:30.632 about 21.21 minutes after the SVOM/ECLAIRs T0 time. We obtained a sequence of 3x200 s exposures in the SDSS r band. The optical counterpart reported by SVOM/COLIBRÍ (FM-GFT) (López-Cámara et al., GCN 42638) is clearly detected in our stacked image. We measure an AB magnitude of r = 21.52 ± 0.15 at a midtime of Tmid − T0 = 26.63 min after the trigger. The photometry was calibrated against nearby Pan-STARRS1 stars and no correction for Galactic dust extinction was applied. This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/42639. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40702] GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42638 SUBJECT: GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection DATE: 25/11/11 06:23:52 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> Diego López-Cámara (UNAM), Antonio de Ugarte Postigo (LAM), Alan M. Watson (UNAM), Benjamin Schneider (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), N. A. Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Yehao Cheng (SWIFAR,YNU), Boting Wang (YNAO): We imaged the field of the SVOM GRB 251111A (Cheng et al., GCN Circ. 42637) using the DDRAGO two-channel wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-11-11 05:21:36 to 05:37:03 UTC (from 11.4 to 26.8 minutes after the trigger) and obtained 13 minutes of simultaneous exposure in the r and z filters. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We detect an uncatalogued source revealed by image subtraction using PanSTARRS as template and consistent with the ECLAIRs 7.55 arcmin error circle (Cheng et al., GCN Circ. 42637) at: RA(J2000) = 02:09:26.82 = 32.361770 degrees Dec(J2000) = 05:13:40.4 = 5.227888 degrees with an uncertainty of 0.5 arcsec. The preliminary magnitude derived for that source is: r = 21.35 +/- 0.05 z = 20.27 +/- 0.05 The source fades during our observations, confirming that it is the optical afterglow of the GRB. The red r-z color might indicate a moderately high redshift or extinction due to dust. Further observations are ongoing. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/42638. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40701] GRB 251111A: SVOM detection of a soft burst
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42637 SUBJECT: GRB 251111A: SVOM detection of a soft burst DATE: 25/11/11 05:40:11 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Yehao Cheng (SWIFAR,YNU), Boting Wang (YNAO), Wenjin Xie, Donghua ZHAO (NAOC), Hatsunegoto Goto (Kanazawa Univ./CEA) report on behalf of the SVOM mission team: At 2025-11-11T05:10:18 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251111A (SVOM burst-id sb25111101). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 7 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 10.57 in the [5-20] keV energy band over a time window of 5.10 seconds starting at 2025-11-11T05:10:15. The localization of the best alert is R.A., Dec. 32.3783, 5.2567 degrees: R.A. (J2000) = 2h09m30.79s Dec. (J2000) = 5d15m24.04s with a 90% confidence level (C.L.) radius of 7.55 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to this burst, but MXT and VT were in the occultation of the Earth. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Yehao Cheng: yhcheng(a)mail.ynu.edu.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42637. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40700] GRB 251103B: Swift-BAT refined analysis
by GCN Circulars 11 Nov '25

11 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42636 SUBJECT: GRB 251103B: Swift-BAT refined analysis DATE: 25/11/11 05:05:46 GMT FROM: Mike Moss at NASA GSFC <mikejmoss3(a)gmail.com> R. Gupta (GSFC), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), S. Lanava (PSU), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+1282 sec from the recent telemetry downlink, we report further analysis of BAT GRB 251103B (trigger #1409824) (Lanava, et al., GCN Circ. 42556). The BAT ground-calculated position is RA, Dec = 105.870, -24.871 deg which is RA(J2000) = 07h 03m 28.7s Dec(J2000) = -24d 52' 14.9" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 99%. The mask-weighted light curve displays a complicated structure with tens of pulses. Significant emission begins at ~T0-110 seconds and ends ~T0+95 seconds. T90 (15-350 keV) is 127.86 +- 22.41 sec (estimated error including systematics). The time-averaged spectrum from T-52.07 to T+92.74 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.79 +- 0.08. The fluence in the 15-150 keV band is 3.5 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+2.00 sec in the 15-150 keV band is 2.9 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1409824 View this GCN Circular online at https://gcn.nasa.gov/circulars/42636. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40699] GRB 251106A: Swift/UVOT Upper Limits
by GCN Circulars 10 Nov '25

10 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42635 SUBJECT: GRB 251106A: Swift/UVOT Upper Limits DATE: 25/11/10 15:56:36 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251106A 4.1 ks after the SVOM/ECLAIRs trigger (Antier et al., GCN Circ. 42605). We do not detect any afterglow consistent with the XRT position (D'Ai et al., GCN Circ. 42611) or optical position (Angulo et al., GCN Circ. 42607). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u 4066 9896 1987 >20.56 u 199146 273340 4837 >21.08 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.016 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42635. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40698] GRB 251105B: Insight-HXMT/HE detection
by GCN Circulars 10 Nov '25

10 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42634 SUBJECT: GRB 251105B: Insight-HXMT/HE detection DATE: 25/11/10 08:51:03 GMT FROM: renyz16607(a)163.com Yang-Zhao Ren, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng (IHEP) report on behalf of the Insight-HXMT team: At 2025-11-05T00:58:34.700 (T0), Insight-HXMT/HE detected a short-duration GRB with extended emission, GRB 251105B, which is also detected by SVOM/GRM (Wang et al., GCN#42586), Fermi/GBM (Fermi GBM team, GCN #42589), and AstroSat/CZTI (Harsha et al., GCN#42591). The Insight-HXMT/HE light curve mainly consists of a narrow, hard spike followed by a long pulse with a T90 of 39.7 +7.9/-2.1 s. The 1s peak rate, measured from T0-0.34 s, is 2439 cnts/sec. Insight-HXMT/HE detected a total of 22413 counts from this burst. The Insight-HXMT /HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251105B.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org View this GCN Circular online at https://gcn.nasa.gov/circulars/42634. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40697] GRB 251106B: Insight-HXMT detection
by GCN Circulars 10 Nov '25

10 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42633 SUBJECT: GRB 251106B: Insight-HXMT detection DATE: 25/11/10 08:36:11 GMT FROM: zhangjinpeng(a)ihep.ac.cn Jin-Peng Zhang, Chen-Wei Wang, Cheng-Kui Li and Shao-Lin Xiong report on behalf of the Insight-HXMT team: At 2025-11-06T18:14:44.000(T0), Insight-HXMT/HE detected the burst GRB 251106B, which is also detected by SVOM/GRM (Wang et al., GCN#42612). The Insight-HXMT/HE light curve mainly consists of several short spikes with a T90 of 1.55 +0.15/-0.35 s. The 1s peak rate, measured from T0+0.275 s, is 1078 cnts/sec. The total counts from this burst is 1511 counts. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251106B.png All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org View this GCN Circular online at https://gcn.nasa.gov/circulars/42633. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40696] LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
by GCN Circulars 10 Nov '25

10 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42632 SUBJECT: LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate DATE: 25/11/10 07:18:02 GMT FROM: Rosa Leticia Becerra Godínez at Instituto de Astronomía, UNAM <rbecerra(a)astro.unam.mx> Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report: We observe the field of the gravitational wave candidate S251108fi (LVKC, GCN Circ. 42624) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on the Sierra of San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of 2025-11-10 UTC. DDOTI observed from 02:22 UTC to 04:35 UTC (T+31.4 h to T+33.6 h after the trigger), with a total exposure time of 72 minutes, pointing the region reported by the IceCube Collaboration (GCN Circ. 42630). Comparing our observations with the USNO-B1 and Pan-STARRS PS1 DR2 catalogues, we identify an uncatalogued source at: RA = 00:57:11.36 (14.2973 d) DEC= +07:39:07.1 (7.6520 d) with a preliminary magnitude AB magnitude of: w = 20.11 +/- 0.11. This source lies outside the IceCube region but within the 90% credible region reported by the LVK Collaboration (GCN Circ. 42628). It is located approximately 4" from a known galaxy with a photometric redshift of z = 0.214 ± 0.031 in the Legacy Survey DR10 (Dey et al. 2019). If they are associated, such a redshift would make a connection with the GW candidate unlikely. However, further observations and analysis are ongoing. This value is not corrected for the Galactic extinction. We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/42632. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40695] GRB 251105A: AstroSat CZTI detection
by GCN Circulars 10 Nov '25

10 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42631 SUBJECT: GRB 251105A: AstroSat CZTI detection DATE: 25/11/10 05:40:22 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Arya (IITB), A. Goyal (IITB), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 251105A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42596), and Swift BAT (J. DeLaunay et al. 2025, GCN 42593). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-11-05 04:41:19.50 UTC. The measured peak count rate associated with the burst is 85 (+32, -10) counts/s above the background in the combined data of three quadrants (out of four), with a total of 1064 (+275, -254) counts. The local mean background count rate was 211 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 28 (+5, -5) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-05 04:41:20.32 UTC. The measured peak count rate associated with the burst is 178 (+72, -15) counts/s above the background in the combined data of all quadrants, with a total of 2223 (+423, -516) counts. The local mean background count rate was 1203 (+6, -5) counts/s. We measure a T90 of 28 (+2, -7) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42631. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40694] LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
by GCN Circulars 09 Nov '25

09 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42630 SUBJECT: LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches DATE: 25/11/09 22:42:06 GMT FROM: Alicia Mand at IceCube/UW-Madison <aemand(a)wisc.edu> IceCube Collaboration (http://icecube.wisc.edu/) reports: Searches for track-like muon neutrino events detected by IceCube consistent with the sky localization of gravitational-wave candidate S251108fi (GCN 42628) in a time range of 1000 seconds centered on the alert event time (2025-11-08 19:05:08.506 UTC to 2025-11-08 19:21:48.506 UTC) have been performed [1,2]. During this time period IceCube was collecting good quality data. Two hypothesis tests were conducted. The first search is a maximum likelihood analysis which searches for a generic point-like neutrino source coincident with the given GW skymap. The second uses a Bayesian approach to quantify the joint GW + neutrino event significance, which assumes a binary merger scenario and accounts for known astrophysical priors, such as GW source distance, in the significance estimate [3]. One track-like event is found in spatial and temporal coincidence with the gravitational-wave candidate S251108fi calculated from the map circulated in the 4-Update notice. This represents an overall p-value of 0.0076 from the generic transient search and an overall p-value of 0.0421 for the Bayesian search. These p-values measure the consistency of the observed track-like events with the known atmospheric backgrounds for this single map (not trials corrected for multiple GW events). The most probable multi-messenger source direction based on the neutrinos and GW skymap is RA 15.12, Dec 9.06 degrees. The reported p-values can differ due to the estimated distance of the GW candidate. The distance is used as a prior in the Bayesian binary merger search, while it is not taken into account in the generic transient point-like source search. The false alarm rate of these coincidences can be obtained by multiplying the p-values with their corresponding GW trigger rates. Further details are available at https://gcn.nasa.gov/missions/icecube. Additional details and updates will be posted at https://roc.icecube.wisc.edu/public/LvkNuTrackSearch/. Properties of the coincident event are shown below. | dt(s) | RA(deg) | Dec(deg) | Angular uncertainty(deg)| p-value(generic transient)| p-value(Bayesian) | |-------|----------|----------|-------------------------|---------------------------|-----------------------| |-242.48 | 15.01 | 9.06 | 1.13 | 0.0076 | 0.0421 | where: dt = Time of track event minus time of GW trigger (sec). Angular uncertainty = Angular uncertainty of track event: the radius of a circle representing 90% CL containment by area. p-value = the p-value for this specific track event from each search. Event p-values are provided when the per-event p-value is less than 0.1 in either search. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu [1] M. G. Aartsen et al 2020 ApJL 898 L10 [2] Abbasi et al. Astrophys.J. 944 (2023) 1, 80 [3] I. Bartos et al. 2019 Phys. Rev. D 100, 083017 View this GCN Circular online at https://gcn.nasa.gov/circulars/42630. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40693] IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 09 Nov '25

09 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42629 SUBJECT: IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/11/09 19:33:46 GMT FROM: Yuhua Yao at IceCube/UW-Madison <yyao255(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-Cascade 251107A (https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/141568_42562719.amon) in a time range of 1000 seconds centered on the alert event time (2025-11-07 20:53:25.880 UTC to 2025-11-07 21:10:05.880 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-Cascade 251107A. We report a p-value of 1.00 in this time window. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.2e+01 to 2.5e+01 GeV cm^-2 within the 90% spatial containment region of IceCube-Cascade 251107A in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 4e+04 GeV and 4e+06 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-11-06 21:01:45.880 UTC to 2025-11-08 21:01:45.880 UTC). In this case, we report a p-value of 0.57, consistent with no significant excess of track events. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.2e+01 to 2.7e+01 GeV cm^-2 within the 90% spatial containment region of IceCube-Cascade 251107A in a 2 day time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/42629. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40692] IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 09 Nov '25

09 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42629 SUBJECT: IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/11/09 19:33:46 GMT FROM: Yuhua Yao at IceCube/UW-Madison <yyao255(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-Cascade 251107A (https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/141568_42562719.amon) in a time range of 1000 seconds centered on the alert event time (2025-11-07 20:53:25.880 UTC to 2025-11-07 21:10:05.880 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-Cascade 251107A. We report a p-value of 1.00 in this time window. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.2e+01 to 2.5e+01 GeV cm^-2 within the 90% spatial containment region of IceCube-Cascade 251107A in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 4e+04 GeV and 4e+06 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-11-06 21:01:45.880 UTC to 2025-11-08 21:01:45.880 UTC). In this case, we report a p-value of 0.57, consistent with no significant excess of track events. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.2e+01 to 2.7e+01 GeV cm^-2 within the 90% spatial containment region of IceCube-Cascade 251107A in a 2 day time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/42629. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40691] LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
by GCN Circulars 09 Nov '25

09 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42628 SUBJECT: LIGO/Virgo/KAGRA S251108fi: Updated Sky localization DATE: 25/11/09 08:53:26 GMT FROM: Abhishek Sharma at IIT Gandhinagar <abhishek.sharma(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S251108fi (GCN Circular 42624). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S251108fi For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 528 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2972 +/- 957 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/42628. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40690] LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
by GCN Circulars 09 Nov '25

09 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42627 SUBJECT: LIGO/Virgo/KAGRA S251108dn: Updated Sky localization DATE: 25/11/09 08:48:37 GMT FROM: Abhishek Sharma at IIT Gandhinagar <abhishek.sharma(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S251108dn (GCN Circular 42619). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S251108dn For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 370 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1089 +/- 246 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/42627. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40689] GRB 251108A: Fermi GBM Final Localization Correction
by GCN Circulars 09 Nov '25

09 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42626 SUBJECT: GRB 251108A: Fermi GBM Final Localization Correction DATE: 25/11/09 00:49:37 GMT FROM: Bagrat Mailyan at Florida Tech <mbagrat(a)gmail.com> The Fermi GBM team reports the detection of a likely SHORT GRB "At 21:19:46.26 UT on 08 November 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251108A (trigger 784329591/251108889). This trigger was initially classified as GRB by the flight software. The on-ground calculated location, using the Fermi GBM trigger data, is RA = 144.63, Dec = 8.03 (J2000 degrees, equivalent to J2000 9h 39m, +8d 2'), with a statistical uncertainty of 3.23 degrees. The angle from the Fermi LAT boresight is 10 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251108889/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251108889/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251108889/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/42626. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40688] Fermi trigger No 784329591: Global MASTER-Net observations report
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42625 SUBJECT: Fermi trigger No 784329591: Global MASTER-Net observations report DATE: 25/11/08 22:16:41 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB251108.89 (trigger No 784329591,09h 39m 43.20s , +04d 40m 48.0s, R=4.06) errorbox 1896 sec after notice time and 1931 sec after trigger time at 2025-11-08 21:51:57 UT, with upper limit up to 16.0 mag. The observations began at zenith distance = 79 deg. The sun altitude is -61.0 deg. The galactic latitude b = 40 deg., longitude l = 231 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3036088 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1961 | 2025-11-08 21:51:57 | MASTER-Kislovodsk | (09h 27m 10.24s , +08d 52m 53.0s) | C | 60 | 15.4 | 1961 | 2025-11-08 21:51:57 | MASTER-Kislovodsk | (09h 31m 07.31s , +08d 30m 22.5s) | C | 60 | 15.5 | 2041 | 2025-11-08 21:53:17 | MASTER-Kislovodsk | (09h 34m 32.46s , +10d 24m 18.7s) | C | 60 | 16.0 | 2120 | 2025-11-08 21:54:36 | MASTER-Kislovodsk | (09h 24m 35.66s , +07d 00m 49.3s) | C | 60 | 15.4 | 2120 | 2025-11-08 21:54:36 | MASTER-Kislovodsk | (09h 28m 31.61s , +06d 38m 17.4s) | C | 60 | 15.6 | 2361 | 2025-11-08 21:58:36 | MASTER-Kislovodsk | (09h 22m 30.89s , +05d 06m 23.8s) | C | 60 | 15.2 | 2361 | 2025-11-08 21:58:37 | MASTER-Kislovodsk | (09h 26m 26.13s , +04d 43m 50.1s) | C | 60 | 15.4 | 2829 | 2025-11-08 22:06:25 | MASTER-Kislovodsk | (09h 42m 37.63s , +08d 54m 28.6s) | C | 60 | 15.7 | 2829 | 2025-11-08 22:06:25 | MASTER-Kislovodsk | (09h 46m 36.13s , +08d 31m 13.0s) | C | 60 | 15.9 | 2909 | 2025-11-08 22:07:44 | MASTER-Kislovodsk | (09h 21m 08.44s , +03d 14m 02.3s) | C | 60 | 14.8 | 2909 | 2025-11-08 22:07:44 | MASTER-Kislovodsk | (09h 25m 04.69s , +02d 50m 48.6s) | C | 60 | 14.8 | 3148 | 2025-11-08 22:11:43 | MASTER-Kislovodsk | (09h 39m 56.05s , +07d 00m 48.8s) | C | 60 | 15.5 | 3148 | 2025-11-08 22:11:44 | MASTER-Kislovodsk | (09h 43m 53.52s , +06d 37m 32.3s) | C | 60 | 15.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42625. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40687] LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42624 SUBJECT: LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate DATE: 25/11/08 19:45:25 GMT FROM: joshua.freed(a)ligo.org The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251108fi during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-11-08 19:13:28.506 UTC (GPS time: 1446664426.506). The candidate was found by the Aframe [1], cWB [2], cWB BBH [3], GstLAL [4], MBTA [5], and PyCBC Live [6] analysis pipelines. S251108fi is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.3e-12 Hz, or about one in 1e4 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251108fi The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [7] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [7] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The source chirp mass falls with highest probability in the bin (22.0, 44.0) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [8], distributed via GCN and SCiMMA notices about 25 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [8], distributed via GCN and SCiMMA notices about 4 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 1524 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 3537 +/- 1032 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Marx et al. PRD 111, 042010 (2025) doi:10.1103/PhysRevD.111.042010 [2] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004 [3] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [4] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [5] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [6] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [7] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [8] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42624. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40686] Fermi trigger No 784279167: Global MASTER-Net observations report
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42623 SUBJECT: Fermi trigger No 784279167: Global MASTER-Net observations report DATE: 25/11/08 16:15:23 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB251108.31 (trigger No 784279167,06h 35m 02.40s , +73d 27m 36.0s, R=4.66) errorbox 29979 sec after notice time and 30021 sec after trigger time at 2025-11-08 15:39:43 UT, with upper limit up to 18.1 mag. The observations began at zenith distance = 61 deg. The sun altitude is -19.5 deg. The galactic latitude b = 25 deg., longitude l = 141 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3035666 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 30051 | 2025-11-08 15:39:43 | MASTER-Kislovodsk | (07h 04m 56.02s , +73d 17m 35.4s) | C | 60 | 17.1 | 30051 | 2025-11-08 15:39:43 | MASTER-Kislovodsk | (07h 18m 49.65s , +72d 53m 17.3s) | C | 60 | 17.6 | 30143 | 2025-11-08 15:41:14 | MASTER-Kislovodsk | (06h 22m 49.76s , +71d 23m 22.2s) | C | 60 | 17.1 | 30144 | 2025-11-08 15:41:15 | MASTER-Kislovodsk | (06h 35m 19.95s , +70d 59m 12.3s) | C | 60 | 17.8 | 30226 | 2025-11-08 15:42:37 | MASTER-Kislovodsk | (06h 12m 21.08s , +73d 19m 19.9s) | C | 60 | 17.3 | 30226 | 2025-11-08 15:42:37 | MASTER-Kislovodsk | (06h 26m 14.47s , +72d 54m 55.0s) | C | 60 | 17.8 | 30306 | 2025-11-08 15:43:57 | MASTER-Kislovodsk | (06h 58m 57.48s , +75d 11m 25.4s) | C | 60 | 17.3 | 30306 | 2025-11-08 15:43:57 | MASTER-Kislovodsk | (07h 14m 33.39s , +74d 46m 47.7s) | C | 60 | 17.8 | 30386 | 2025-11-08 15:45:18 | MASTER-Kislovodsk | (07h 10m 21.00s , +71d 23m 25.8s) | C | 60 | 17.2 | 30386 | 2025-11-08 15:45:18 | MASTER-Kislovodsk | (07h 22m 51.41s , +70d 59m 07.0s) | C | 60 | 17.8 | 30466 | 2025-11-08 15:46:38 | MASTER-Kislovodsk | (05h 59m 42.72s , +75d 13m 28.7s) | C | 60 | 17.4 | 30466 | 2025-11-08 15:46:38 | MASTER-Kislovodsk | (06h 15m 17.99s , +74d 48m 38.2s) | C | 60 | 18.1 | 30546 | 2025-11-08 15:47:57 | MASTER-Kislovodsk | (06h 51m 33.54s , +77d 04m 04.7s) | C | 60 | 17.2 | 30546 | 2025-11-08 15:47:58 | MASTER-Kislovodsk | (07h 09m 18.89s , +76d 38m 56.3s) | C | 60 | 17.8 | 30626 | 2025-11-08 15:49:18 | MASTER-Kislovodsk | (06h 31m 59.52s , +69d 30m 50.0s) | C | 60 | 17.0 | 30626 | 2025-11-08 15:49:18 | MASTER-Kislovodsk | (06h 43m 23.61s , +69d 06m 38.5s) | C | 60 | 17.7 | 30787 | 2025-11-08 15:51:58 | MASTER-Kislovodsk | (05h 43m 40.85s , +77d 09m 58.1s) | C | 60 | 17.0 | 30787 | 2025-11-08 15:51:58 | MASTER-Kislovodsk | (06h 01m 36.06s , +76d 44m 46.8s) | C | 60 | 18.0 | 30867 | 2025-11-08 15:53:19 | MASTER-Kislovodsk | (06h 42m 16.62s , +78d 58m 54.4s) | C | 60 | 17.3 | 30867 | 2025-11-08 15:53:19 | MASTER-Kislovodsk | (07h 03m 02.62s , +78d 33m 30.5s) | C | 60 | 18.0 | 30947 | 2025-11-08 15:54:38 | MASTER-Kislovodsk | (07h 57m 46.40s , +73d 16m 03.6s) | C | 60 | 17.1 | 31045 | 2025-11-08 15:56:17 | MASTER-Kislovodsk | (05h 48m 45.00s , +69d 33m 17.8s) | C | 60 | 17.1 | 31045 | 2025-11-08 15:56:17 | MASTER-Kislovodsk | (06h 00m 11.32s , +69d 08m 50.8s) | C | 60 | 17.5 | 31125 | 2025-11-08 15:57:36 | MASTER-Kislovodsk | (05h 43m 39.70s , +78d 38m 58.2s) | C | 60 | 17.9 | 31204 | 2025-11-08 15:58:56 | MASTER-Kislovodsk | (05h 35m 23.59s , +71d 26m 31.9s) | C | 60 | 17.2 | 31205 | 2025-11-08 15:58:56 | MASTER-Kislovodsk | (05h 47m 57.39s , +71d 01m 58.5s) | C | 60 | 17.7 | 31284 | 2025-11-08 16:00:16 | MASTER-Kislovodsk | (05h 19m 36.38s , +73d 21m 51.5s) | C | 60 | 17.2 | 31284 | 2025-11-08 16:00:16 | MASTER-Kislovodsk | (05h 33m 32.73s , +72d 57m 04.6s) | C | 60 | 17.8 | 31407 | 2025-11-08 16:02:19 | MASTER-Kislovodsk | (07h 57m 57.10s , +71d 20m 23.5s) | C | 60 | 17.1 | 31487 | 2025-11-08 16:03:39 | MASTER-Kislovodsk | (07h 58m 20.11s , +75d 08m 19.9s) | C | 60 | 17.2 | 31567 | 2025-11-08 16:04:59 | MASTER-Kislovodsk | (06h 40m 00.61s , +67d 37m 33.6s) | C | 60 | 17.0 | 31567 | 2025-11-08 16:04:59 | MASTER-Kislovodsk | (06h 50m 28.66s , +67d 13m 08.7s) | C | 60 | 17.5 | 31648 | 2025-11-08 16:06:20 | MASTER-Kislovodsk | (05h 00m 19.14s , +75d 16m 51.6s) | C | 60 | 17.2 | 31648 | 2025-11-08 16:06:20 | MASTER-Kislovodsk | (05h 15m 58.57s , +74d 51m 43.2s) | C | 60 | 17.7 | 31764 | 2025-11-08 16:08:16 | MASTER-Kislovodsk | (07h 59m 35.77s , +77d 04m 16.4s) | C | 60 | 17.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42623. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40685] SVOM GRB251108.54: Global MASTER-Net observations report
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42622 SUBJECT: SVOM GRB251108.54: Global MASTER-Net observations report DATE: 25/11/08 13:42:25 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the SVOM GRB251108.54 (trigger No 1762606617,10h 51m 27.41s , +61d 22m 00.5s, R=1) errorbox 27 sec after notice time and 57 sec after trigger time at 2025-11-08 12:57:54 UT, with upper limit up to 14.6 mag. The observations began at zenith distance = 67 deg. The sun altitude is -32.8 deg. The galactic latitude b = 51 deg., longitude l = 145 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3035823 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 63 | 2025-11-08 12:57:54 | MASTER-Tunka | (10h 52m 29.63s , +61d 58m 59.2s) | P- | 10 | 13.2 | 63 | 2025-11-08 12:57:54 | MASTER- | (10h 51m 53.18s , +62d 04m 17.1s) | C | 10 | 17.1 | 86 | 2025-11-08 12:58:13 | MASTER-Tunka | (10h 52m 29.56s , +61d 59m 00.9s) | P- | 20 | 14.0 | 86 | 2025-11-08 12:58:13 | MASTER- | (10h 51m 53.22s , +62d 04m 17.9s) | C | 20 | 17.3 | 110 | 2025-11-08 12:58:37 | MASTER-Tunka | (10h 52m 29.57s , +61d 59m 01.1s) | P- | 20 | 13.6 | 110 | 2025-11-08 12:58:37 | MASTER- | (10h 51m 53.24s , +62d 04m 18.4s) | C | 20 | 17.5 | 134 | 2025-11-08 12:59:00 | MASTER-Tunka | (10h 52m 29.60s , +61d 59m 02.1s) | P- | 20 | 13.8 | 134 | 2025-11-08 12:59:00 | MASTER- | (10h 51m 53.20s , +62d 04m 19.3s) | C | 20 | 17.4 | 162 | 2025-11-08 12:59:24 | MASTER-Tunka | (10h 52m 29.47s , +61d 59m 03.0s) | P- | 30 | 13.8 | 162 | 2025-11-08 12:59:24 | MASTER- | (10h 51m 53.19s , +62d 04m 19.8s) | C | 30 | 17.6 | 201 | 2025-11-08 12:59:57 | MASTER-Tunka | (10h 52m 29.45s , +61d 59m 03.8s) | P- | 40 | 14.1 | 201 | 2025-11-08 12:59:57 | MASTER- | (10h 51m 53.15s , +62d 04m 20.3s) | C | 40 | 17.7 | 245 | 2025-11-08 13:00:42 | MASTER-Tunka | (10h 52m 29.33s , +61d 59m 05.0s) | P- | 40 | 13.8 | 245 | 2025-11-08 13:00:42 | MASTER- | (10h 51m 53.04s , +62d 04m 21.0s) | C | 40 | 17.5 | 293 | 2025-11-08 13:01:25 | MASTER-Tunka | (10h 52m 29.39s , +61d 59m 06.3s) | P- | 50 | 14.0 | 293 | 2025-11-08 13:01:25 | MASTER- | (10h 51m 53.02s , +62d 04m 22.7s) | C | 50 | 18.0 | 352 | 2025-11-08 13:02:18 | MASTER-Tunka | (10h 52m 29.17s , +61d 59m 07.7s) | P- | 60 | 14.1 | 352 | 2025-11-08 13:02:18 | MASTER- | (10h 51m 52.87s , +62d 04m 24.3s) | C | 60 | 17.7 | 416 | 2025-11-08 13:03:22 | MASTER-Tunka | (10h 52m 29.04s , +61d 59m 09.2s) | P- | 60 | 14.1 | 416 | 2025-11-08 13:03:22 | MASTER- | (10h 51m 52.69s , +62d 04m 26.3s) | C | 60 | 17.8 | 479 | 2025-11-08 13:04:26 | MASTER-Tunka | (10h 52m 28.87s , +61d 59m 10.6s) | P- | 60 | 14.1 | 479 | 2025-11-08 13:04:26 | MASTER- | (10h 51m 52.49s , +62d 04m 27.9s) | C | 60 | 17.8 | 543 | 2025-11-08 13:05:29 | MASTER-Tunka | (10h 52m 28.81s , +61d 59m 12.1s) | P- | 60 | 14.0 | 543 | 2025-11-08 13:05:30 | MASTER- | (10h 51m 52.28s , +62d 04m 29.4s) | C | 60 | 17.7 | 606 | 2025-11-08 13:06:33 | MASTER-Tunka | (10h 52m 28.72s , +61d 59m 13.7s) | P- | 60 | 14.0 | 606 | 2025-11-08 13:06:33 | MASTER- | (10h 51m 52.11s , +62d 04m 31.4s) | C | 60 | 17.6 | 670 | 2025-11-08 13:07:37 | MASTER-Tunka | (10h 52m 28.53s , +61d 59m 15.6s) | P- | 60 | 14.1 | 670 | 2025-11-08 13:07:37 | MASTER- | (10h 51m 51.90s , +62d 04m 32.7s) | C | 60 | 17.7 | 733 | 2025-11-08 13:08:40 | MASTER-Tunka | (10h 52m 28.39s , +61d 59m 18.2s) | P- | 60 | 14.0 | 733 | 2025-11-08 13:08:40 | MASTER- | (10h 51m 51.73s , +62d 04m 35.2s) | C | 60 | 17.7 | 797 | 2025-11-08 13:09:43 | MASTER-Tunka | (10h 52m 28.30s , +61d 59m 20.7s) | P- | 60 | 14.0 | 797 | 2025-11-08 13:09:43 | MASTER- | (10h 51m 51.55s , +62d 04m 37.6s) | C | 60 | 17.7 | 860 | 2025-11-08 13:10:46 | MASTER-Tunka | (10h 52m 28.10s , +61d 59m 22.2s) | P- | 60 | 13.9 | 860 | 2025-11-08 13:10:46 | MASTER- | (10h 51m 51.36s , +62d 04m 39.4s) | C | 60 | 17.6 | 924 | 2025-11-08 13:11:50 | MASTER-Tunka | (10h 52m 28.06s , +61d 59m 24.0s) | P- | 60 | 13.8 | 924 | 2025-11-08 13:11:50 | MASTER- | (10h 51m 51.13s , +62d 04m 41.3s) | C | 60 | 17.6 | 987 | 2025-11-08 13:12:53 | MASTER-Tunka | (10h 52m 27.80s , +61d 59m 25.9s) | P- | 60 | 13.9 | 987 | 2025-11-08 13:12:53 | MASTER- | (10h 51m 50.91s , +62d 04m 43.6s) | C | 60 | 17.7 | 1050 | 2025-11-08 13:13:57 | MASTER-Tunka | (10h 52m 27.59s , +61d 59m 28.2s) | P- | 60 | 14.0 | 1050 | 2025-11-08 13:13:57 | MASTER- | (10h 51m 50.72s , +62d 04m 45.4s) | C | 60 | 17.7 | 1114 | 2025-11-08 13:15:00 | MASTER-Tunka | (10h 52m 27.52s , +61d 59m 30.2s) | P- | 60 | 13.7 | 1114 | 2025-11-08 13:15:01 | MASTER- | (10h 51m 50.53s , +62d 04m 47.7s) | C | 60 | 17.7 | 1177 | 2025-11-08 13:16:04 | MASTER-Tunka | (10h 52m 27.42s , +61d 59m 31.9s) | P- | 60 | 13.5 | 1177 | 2025-11-08 13:16:04 | MASTER- | (10h 51m 50.36s , +62d 04m 49.5s) | C | 60 | 17.7 | 1241 | 2025-11-08 13:17:07 | MASTER-Tunka | (10h 52m 27.22s , +61d 59m 33.3s) | P- | 60 | 14.0 | 1241 | 2025-11-08 13:17:07 | MASTER- | (10h 51m 50.27s , +62d 04m 50.8s) | C | 60 | 17.6 | 1304 | 2025-11-08 13:18:11 | MASTER-Tunka | (10h 52m 27.00s , +61d 59m 34.6s) | P- | 60 | 14.0 | 1304 | 2025-11-08 13:18:11 | MASTER- | (10h 51m 50.06s , +62d 04m 52.4s) | C | 60 | 17.6 | 1368 | 2025-11-08 13:19:14 | MASTER-Tunka | (10h 52m 26.80s , +61d 59m 36.0s) | P- | 60 | 14.0 | 1368 | 2025-11-08 13:19:14 | MASTER- | (10h 51m 49.88s , +62d 04m 54.2s) | C | 60 | 17.6 | 1431 | 2025-11-08 13:20:18 | MASTER-Tunka | (10h 52m 26.66s , +61d 59m 37.8s) | P- | 60 | 14.0 | 1431 | 2025-11-08 13:20:18 | MASTER- | (10h 51m 49.72s , +62d 04m 56.1s) | C | 60 | 17.7 | 1495 | 2025-11-08 13:21:21 | MASTER-Tunka | (10h 52m 26.53s , +61d 59m 40.5s) | P- | 60 | 14.0 | 1495 | 2025-11-08 13:21:22 | MASTER- | (10h 51m 49.55s , +62d 04m 57.7s) | C | 60 | 17.6 | 1559 | 2025-11-08 13:22:25 | MASTER-Tunka | (10h 52m 26.30s , +61d 59m 41.9s) | P- | 60 | 14.0 | 1559 | 2025-11-08 13:22:25 | MASTER- | (10h 51m 49.37s , +62d 04m 59.7s) | C | 60 | 17.6 | 1622 | 2025-11-08 13:23:28 | MASTER-Tunka | (10h 52m 25.91s , +61d 59m 40.4s) | P- | 60 | 14.4 | 1622 | 2025-11-08 13:23:28 | MASTER- | (10h 51m 49.17s , +62d 05m 01.6s) | C | 60 | 17.5 | 1685 | 2025-11-08 13:24:32 | MASTER-Tunka | (10h 52m 26.42s , +61d 59m 43.8s) | P- | 60 | 14.3 | 1685 | 2025-11-08 13:24:32 | MASTER- | (10h 51m 48.97s , +62d 05m 03.7s) | C | 60 | 17.5 | 1749 | 2025-11-08 13:25:35 | MASTER-Tunka | (10h 52m 25.94s , +61d 59m 48.0s) | P- | 60 | 13.3 | 1749 | 2025-11-08 13:25:35 | MASTER- | (10h 51m 48.81s , +62d 05m 05.5s) | C | 60 | 17.6 | 1812 | 2025-11-08 13:26:39 | MASTER-Tunka | (10h 52m 25.57s , +61d 59m 48.7s) | P- | 60 | 13.8 | 1812 | 2025-11-08 13:26:39 | MASTER- | (10h 51m 48.58s , +62d 05m 07.2s) | C | 60 | 17.5 | 1876 | 2025-11-08 13:27:42 | MASTER-Tunka | (10h 52m 25.27s , +61d 59m 47.8s) | P- | 60 | 14.5 | 1876 | 2025-11-08 13:27:42 | MASTER- | (10h 51m 48.42s , +62d 05m 09.3s) | C | 60 | 17.6 | 1939 | 2025-11-08 13:28:45 | MASTER- | (10h 51m 48.26s , +62d 05m 11.4s) | C | 60 | 17.7 | 2003 | 2025-11-08 13:29:49 | MASTER-Tunka | (10h 52m 25.20s , +61d 59m 52.2s) | P- | 60 | 14.4 | 2003 | 2025-11-08 13:29:49 | MASTER- | (10h 51m 48.10s , +62d 05m 13.2s) | C | 60 | 17.6 | 2066 | 2025-11-08 13:30:53 | MASTER-Tunka | (10h 52m 25.03s , +61d 59m 53.5s) | P- | 60 | 14.4 | 2066 | 2025-11-08 13:30:53 | MASTER- | (10h 51m 47.91s , +62d 05m 15.6s) | C | 60 | 17.7 | 2129 | 2025-11-08 13:31:56 | MASTER-Tunka | (10h 52m 24.92s , +61d 59m 55.3s) | P- | 60 | 14.6 | 2129 | 2025-11-08 13:31:56 | MASTER- | (10h 51m 47.74s , +62d 05m 17.5s) | C | 60 | 17.8 | 2193 | 2025-11-08 13:32:59 | MASTER-Tunka | (10h 52m 24.62s , +61d 59m 58.2s) | P- | 60 | 14.6 | 2193 | 2025-11-08 13:32:59 | MASTER- | (10h 51m 47.50s , +62d 05m 19.7s) | C | 60 | 17.6 | 2256 | 2025-11-08 13:34:03 | MASTER-Tunka | (10h 52m 24.02s , +62d 00m 01.1s) | P- | 60 | 14.4 | 2256 | 2025-11-08 13:34:03 | MASTER- | (10h 51m 47.34s , +62d 05m 21.5s) | C | 60 | 17.7 | 2320 | 2025-11-08 13:35:06 | MASTER-Tunka | (10h 52m 24.16s , +62d 00m 04.2s) | P- | 60 | 14.0 | 2320 | 2025-11-08 13:35:06 | MASTER- | (10h 51m 47.12s , +62d 05m 22.9s) | C | 60 | 17.5 | 2383 | 2025-11-08 13:36:10 | MASTER-Tunka | (10h 52m 23.83s , +62d 00m 02.5s) | P- | 60 | 14.5 | 2383 | 2025-11-08 13:36:10 | MASTER- | (10h 51m 46.92s , +62d 05m 24.8s) | C | 60 | 17.7 | 2447 | 2025-11-08 13:37:13 | MASTER-Tunka | (10h 52m 23.41s , +62d 00m 06.4s) | P- | 60 | 14.4 | 2447 | 2025-11-08 13:37:13 | MASTER- | (10h 51m 46.70s , +62d 05m 26.9s) | C | 60 | 17.5 | 2510 | 2025-11-08 13:38:16 | MASTER-Tunka | (10h 52m 23.82s , +62d 00m 07.0s) | P- | 60 | 14.4 | 2510 | 2025-11-08 13:38:16 | MASTER- | (10h 51m 46.49s , +62d 05m 28.5s) | C | 60 | 17.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42622. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40684] GRB 251102B: SVOM/GRM observation
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42621 SUBJECT: GRB 251102B: SVOM/GRM observation DATE: 25/11/08 13:30:33 GMT FROM: yzh807926(a)163.com SVOM/GRM team: Zheng-Hang Yu, Chen-Wei Wang, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Sebastien Guillot (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground by a burst GRB 251102B at 2025-11-02T21:15:53.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #42533). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single peak with a T90 of 3.5 +1.5/-1.0 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251102B.png In addition, the position of this burst, as determined by Fermi/GBM (RA= 110.6, DEC= -69.7, GCN#42533), is located at about 83 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-6 to T0+4 s is best fitted by a power law function. The power law index is -1.98 +0.01/-0.03. The event fluence (10-1000 keV) in this time interval is (1.25 +0.16/-0.15)E-6 erg/cm^2. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Zheng-Hang Yu(IHEP)(zhyu(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42621. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40683] Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42620 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB DATE: 25/11/08 12:01:17 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca(a)unitn.it> A. Holzmann Airasca (UniTrento and INFN Bari) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 784279167/251108305 at 07:19:22.22 UT on 08 November 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/42620. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40682] LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42619 SUBJECT: LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate DATE: 25/11/08 11:42:05 GMT FROM: FRANCESCO STOLZI at Unisi <stolzi3(a)unisi.it> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251108dn during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-11-08 10:32:43.578 UTC (GPS time: 1446633181.578). The candidate was found by the Aframe [1], cWB BBH [2], GstLAL [3], MBTA [4], PyCBC Live [5], and SPIIR [6] analysis pipelines. S251108dn is an event of interest because its false alarm rate, as estimated by the online analysis, is 9.4e-18 Hz, or about one in 1e10 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251108dn The classification of the GW signal, in order of descending probability, is BBH (>99%), NSBH (<1%), Terrestrial (<1%), or BNS (<1%). Noise transients (glitches) were present in the LIGO Livingston and Virgo detector data within two seconds of the event time, which may affect the parameters or the significance of the candidate. Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [7] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [7] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 2%. The source chirp mass falls with highest probability in the bin (5.5, 11.0) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [8], distributed via GCN and SCiMMA notices about 26 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [8], distributed via GCN and SCiMMA notices about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 697 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1165 +/- 309 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Marx et al. PRD 111, 042010 (2025) doi:10.1103/PhysRevD.111.042010 [2] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [3] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [4] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [5] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [6] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [7] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [8] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42619. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40681] The EP-WXT trigger 01709248051 is likely a flaring star
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42618 SUBJECT: The EP-WXT trigger 01709248051 is likely a flaring star DATE: 25/11/08 01:10:53 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. H. Cheng (YNU), C. Y. Dai (NJU), R. D. Liang, W. Chen, H. Sun (NAO,CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709248051 at the time of 2025-11-08T00:00:49, is likely a stellar flare associated with the High Proper Motion Star [GBA2007] 680. The estimated flux of the flare is around 6 x 10^(-11) erg/s/cm^2 in 0.5-4 keV, corresponding to an X-ray luminosity of around 5.1 x 10^(31) erg/s. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42618. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40680] SVOM GRB251106.83: Global MASTER-Net observations report
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42617 SUBJECT: SVOM GRB251106.83: Global MASTER-Net observations report DATE: 25/11/07 19:56:30 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the SVOM GRB251106.83 (trigger No 1762458982,15h 39m 01.49s , +63d 21m 52.9s, R=0.1547) errorbox 57 sec after notice time and 1565 sec after trigger time at 2025-11-06 20:22:27 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 73 deg. The sun altitude is -62.3 deg. The galactic latitude b = 45 deg., longitude l = 98 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3034620 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1626 | 2025-11-06 20:22:27 | MASTER-Kislovodsk | (15h 37m 28.85s , +63d 06m 03.4s) | P- | 120 | 15.6 | 1766 | 2025-11-06 20:24:47 | MASTER-Kislovodsk | (15h 37m 29.81s , +63d 05m 56.6s) | P- | 120 | 15.6 | 1766 | 2025-11-06 20:24:47 | MASTER-Kislovodsk | (15h 37m 42.69s , +63d 28m 24.2s) | P| | 120 | 17.2 | 1905 | 2025-11-06 20:27:07 | MASTER-Kislovodsk | (15h 37m 30.71s , +63d 05m 51.6s) | P- | 120 | 15.5 | 1905 | 2025-11-06 20:27:07 | MASTER-Kislovodsk | (15h 37m 43.57s , +63d 28m 18.7s) | P| | 120 | 17.3 | 2045 | 2025-11-06 20:29:27 | MASTER-Kislovodsk | (15h 37m 31.56s , +63d 05m 46.7s) | P- | 120 | 15.6 | 2045 | 2025-11-06 20:29:27 | MASTER-Kislovodsk | (15h 37m 44.37s , +63d 28m 13.8s) | P| | 120 | 17.2 | 2155 | 2025-11-06 20:31:47 | MASTER-Kislovodsk | (15h 37m 25.48s , +63d 04m 04.1s) | C | 60 | 17.0 | 2275 | 2025-11-06 20:31:47 | MASTER-Kislovodsk | (15h 37m 25.50s , +63d 04m 04.1s) | C | 300 | 17.5 | Coadd 2155 | 2025-11-06 20:31:47 | MASTER-Kislovodsk | (15h 37m 38.06s , +63d 26m 36.1s) | C | 60 | 17.4 | 2873 | 2025-11-06 20:43:45 | MASTER-Kislovodsk | (15h 36m 59.84s , +63d 06m 24.9s) | C | 60 | 17.0 | 2933 | 2025-11-06 20:43:45 | MASTER-Kislovodsk | (15h 36m 59.83s , +63d 06m 24.9s) | C | 180 | 17.8 | Coadd 2873 | 2025-11-06 20:43:45 | MASTER-Kislovodsk | (15h 37m 12.09s , +63d 29m 02.0s) | C | 60 | 17.4 | 2953 | 2025-11-06 20:45:05 | MASTER-Kislovodsk | (15h 37m 04.06s , +63d 05m 20.5s) | C | 60 | 17.1 | 2953 | 2025-11-06 20:45:05 | MASTER-Kislovodsk | (15h 37m 16.46s , +63d 27m 56.8s) | C | 60 | 17.5 | 3033 | 2025-11-06 20:46:25 | MASTER-Kislovodsk | (15h 36m 58.81s , +63d 04m 17.3s) | C | 60 | 17.0 | 3033 | 2025-11-06 20:46:25 | MASTER-Kislovodsk | (15h 37m 11.34s , +63d 26m 52.9s) | C | 60 | 17.4 | 3143 | 2025-11-06 20:47:45 | MASTER-Kislovodsk | (15h 37m 04.62s , +63d 04m 30.1s) | C | 120 | 17.3 | 3144 | 2025-11-06 20:47:45 | MASTER-Kislovodsk | (15h 37m 17.42s , +63d 27m 05.1s) | C | 120 | 17.4 | 3305 | 2025-11-06 20:50:26 | MASTER-Kislovodsk | (15h 37m 04.51s , +63d 05m 55.6s) | C | 120 | 17.3 | 3305 | 2025-11-06 20:50:26 | MASTER-Kislovodsk | (15h 37m 17.54s , +63d 28m 30.4s) | C | 120 | 17.5 | 3444 | 2025-11-06 20:52:46 | MASTER-Kislovodsk | (15h 37m 05.48s , +63d 04m 10.8s) | C | 120 | 17.2 | 3564 | 2025-11-06 20:52:46 | MASTER-Kislovodsk | (15h 37m 05.48s , +63d 04m 10.8s) | C | 360 | 17.9 | Coadd 3444 | 2025-11-06 20:52:46 | MASTER-Kislovodsk | (15h 37m 18.70s , +63d 26m 45.1s) | C | 120 | 17.5 | 3584 | 2025-11-06 20:55:05 | MASTER-Kislovodsk | (15h 37m 07.60s , +63d 05m 54.6s) | C | 120 | 17.2 | 3584 | 2025-11-06 20:55:05 | MASTER-Kislovodsk | (15h 37m 20.97s , +63d 28m 28.6s) | C | 120 | 17.4 | 3724 | 2025-11-06 20:57:25 | MASTER-Kislovodsk | (15h 37m 04.73s , +63d 05m 01.2s) | C | 120 | 17.2 | 3724 | 2025-11-06 20:57:26 | MASTER-Kislovodsk | (15h 37m 18.15s , +63d 27m 35.0s) | C | 120 | 17.4 | 3864 | 2025-11-06 20:59:45 | MASTER-Kislovodsk | (15h 37m 04.57s , +63d 05m 58.7s) | C | 120 | 17.1 | 3924 | 2025-11-06 20:59:45 | MASTER-Kislovodsk | (15h 37m 04.57s , +63d 05m 58.8s) | C | 240 | 17.5 | Coadd 3864 | 2025-11-06 20:59:45 | MASTER-Kislovodsk | (15h 37m 18.12s , +63d 28m 32.3s) | C | 120 | 17.4 | 3974 | 2025-11-06 21:02:05 | MASTER-Kislovodsk | (15h 37m 10.31s , +63d 04m 57.0s) | C | 60 | 16.8 | 3974 | 2025-11-06 21:02:05 | MASTER-Kislovodsk | (15h 37m 23.89s , +63d 27m 30.6s) | C | 60 | 17.2 | 4054 | 2025-11-06 21:03:25 | MASTER-Kislovodsk | (15h 37m 05.87s , +63d 03m 55.5s) | C | 60 | 16.8 | 4054 | 2025-11-06 21:03:25 | MASTER-Kislovodsk | (15h 37m 19.52s , +63d 26m 29.2s) | C | 60 | 17.2 | 4134 | 2025-11-06 21:04:45 | MASTER-Kislovodsk | (15h 37m 13.13s , +63d 04m 18.9s) | C | 60 | 16.8 | 4194 | 2025-11-06 21:04:45 | MASTER-Kislovodsk | (15h 37m 13.12s , +63d 04m 18.9s) | C | 180 | 17.3 | Coadd 4134 | 2025-11-06 21:04:45 | MASTER-Kislovodsk | (15h 37m 26.81s , +63d 26m 52.7s) | C | 60 | 17.1 | 4214 | 2025-11-06 21:06:05 | MASTER-Kislovodsk | (15h 37m 10.83s , +63d 05m 52.4s) | C | 60 | 16.6 | 4214 | 2025-11-06 21:06:05 | MASTER-Kislovodsk | (15h 37m 24.56s , +63d 28m 26.3s) | C | 60 | 16.9 | 4294 | 2025-11-06 21:07:25 | MASTER-Kislovodsk | (15h 37m 24.19s , +63d 26m 54.6s) | C | 60 | 16.9 | 4294 | 2025-11-06 21:07:25 | MASTER-Kislovodsk | (15h 37m 10.45s , +63d 04m 20.8s) | C | 60 | 16.4 | 4373 | 2025-11-06 21:08:45 | MASTER-Kislovodsk | (15h 37m 28.61s , +63d 28m 10.5s) | C | 60 | 16.8 | 4373 | 2025-11-06 21:08:45 | MASTER-Kislovodsk | (15h 37m 14.90s , +63d 05m 36.8s) | C | 60 | 16.5 | 4433 | 2025-11-06 21:08:45 | MASTER-Kislovodsk | (15h 37m 14.90s , +63d 05m 36.9s) | C | 180 | 17.0 | Coadd 4453 | 2025-11-06 21:10:04 | MASTER-Kislovodsk | (15h 37m 22.44s , +63d 27m 24.6s) | C | 60 | 16.7 | 4453 | 2025-11-06 21:10:04 | MASTER-Kislovodsk | (15h 37m 08.69s , +63d 04m 51.0s) | C | 60 | 16.4 | 4533 | 2025-11-06 21:11:24 | MASTER-Kislovodsk | (15h 37m 24.05s , +63d 28m 23.8s) | C | 60 | 16.7 | 4533 | 2025-11-06 21:11:24 | MASTER-Kislovodsk | (15h 37m 10.40s , +63d 05m 50.5s) | C | 60 | 16.3 | 4718 | 2025-11-06 21:14:29 | MASTER-Kislovodsk | (15h 37m 24.27s , +63d 28m 40.2s) | C | 60 | 16.6 | 4718 | 2025-11-06 21:14:29 | MASTER-Kislovodsk | (15h 37m 08.78s , +63d 05m 48.3s) | C | 60 | 16.3 | 4778 | 2025-11-06 21:14:29 | MASTER-Kislovodsk | (15h 37m 08.78s , +63d 05m 48.4s) | C | 180 | 17.0 | Coadd 4797 | 2025-11-06 21:15:49 | MASTER-Kislovodsk | (15h 37m 30.85s , +63d 27m 38.6s) | C | 60 | 16.6 | 4797 | 2025-11-06 21:15:49 | MASTER-Kislovodsk | (15h 37m 15.47s , +63d 04m 46.6s) | C | 60 | 16.2 | 4877 | 2025-11-06 21:17:09 | MASTER-Kislovodsk | (15h 37m 09.03s , +63d 03m 45.3s) | C | 60 | 16.1 | 4877 | 2025-11-06 21:17:09 | MASTER-Kislovodsk | (15h 37m 24.31s , +63d 26m 37.5s) | C | 60 | 16.4 | 4957 | 2025-11-06 21:18:28 | MASTER-Kislovodsk | (15h 37m 31.56s , +63d 27m 02.7s) | C | 60 | 16.4 | 4957 | 2025-11-06 21:18:28 | MASTER-Kislovodsk | (15h 37m 16.46s , +63d 04m 10.3s) | C | 60 | 16.1 | 5077 | 2025-11-06 21:18:28 | MASTER-Kislovodsk | (15h 37m 16.46s , +63d 04m 10.3s) | C | 300 | 17.1 | Coadd 5067 | 2025-11-06 21:19:48 | MASTER-Kislovodsk | (15h 37m 29.80s , +63d 28m 18.5s) | C | 120 | 16.6 | 5067 | 2025-11-06 21:19:48 | MASTER-Kislovodsk | (15h 37m 14.41s , +63d 05m 26.3s) | C | 120 | 16.5 | 5207 | 2025-11-06 21:22:09 | MASTER-Kislovodsk | (15h 37m 30.85s , +63d 27m 02.1s) | C | 120 | 16.7 | 5208 | 2025-11-06 21:22:09 | MASTER-Kislovodsk | (15h 37m 15.48s , +63d 04m 10.2s) | C | 120 | 16.5 | 5347 | 2025-11-06 21:24:28 | MASTER-Kislovodsk | (15h 37m 35.95s , +63d 28m 23.2s) | C | 120 | 16.8 | 5347 | 2025-11-06 21:24:28 | MASTER-Kislovodsk | (15h 37m 20.33s , +63d 05m 31.7s) | C | 120 | 16.6 | 5467 | 2025-11-06 21:24:28 | MASTER-Kislovodsk | (15h 37m 20.33s , +63d 05m 31.7s) | C | 360 | 17.3 | Coadd 5487 | 2025-11-06 21:26:48 | MASTER-Kislovodsk | (15h 37m 30.28s , +63d 27m 30.2s) | C | 120 | 17.0 | 5487 | 2025-11-06 21:26:48 | MASTER-Kislovodsk | (15h 37m 14.65s , +63d 04m 38.6s) | C | 120 | 16.7 | 5627 | 2025-11-06 21:29:08 | MASTER-Kislovodsk | (15h 37m 30.44s , +63d 28m 29.3s) | C | 120 | 17.0 | 5627 | 2025-11-06 21:29:08 | MASTER-Kislovodsk | (15h 37m 14.73s , +63d 05m 38.3s) | C | 120 | 16.8 | 5767 | 2025-11-06 21:31:29 | MASTER-Kislovodsk | (15h 37m 22.89s , +63d 04m 37.5s) | C | 120 | 16.9 | 5887 | 2025-11-06 21:31:29 | MASTER-Kislovodsk | (15h 37m 22.90s , +63d 04m 37.6s) | C | 360 | 17.5 | Coadd 5767 | 2025-11-06 21:31:29 | MASTER-Kislovodsk | (15h 37m 38.60s , +63d 27m 28.5s) | C | 120 | 17.3 | 5907 | 2025-11-06 21:33:48 | MASTER-Kislovodsk | (15h 37m 34.50s , +63d 26m 28.0s) | C | 120 | 17.1 | 5907 | 2025-11-06 21:33:48 | MASTER-Kislovodsk | (15h 37m 18.97s , +63d 03m 36.8s) | C | 120 | 16.9 | 6047 | 2025-11-06 21:36:08 | MASTER-Kislovodsk | (15h 37m 41.42s , +63d 26m 50.4s) | C | 120 | 17.1 | 6047 | 2025-11-06 21:36:08 | MASTER-Kislovodsk | (15h 37m 25.84s , +63d 03m 59.8s) | C | 120 | 16.9 | 6187 | 2025-11-06 21:38:28 | MASTER-Kislovodsk | (15h 37m 39.82s , +63d 28m 06.3s) | C | 120 | 17.1 | 6187 | 2025-11-06 21:38:28 | MASTER-Kislovodsk | (15h 37m 24.04s , +63d 05m 16.2s) | C | 120 | 16.9 | 6307 | 2025-11-06 21:38:28 | MASTER-Kislovodsk | (15h 37m 24.05s , +63d 05m 16.2s) | C | 360 | 17.6 | Coadd 6326 | 2025-11-06 21:40:48 | MASTER-Kislovodsk | (15h 37m 24.02s , +63d 03m 41.3s) | C | 120 | 16.9 | 6326 | 2025-11-06 21:40:48 | MASTER-Kislovodsk | (15h 37m 40.06s , +63d 26m 31.0s) | C | 120 | 17.0 | 6466 | 2025-11-06 21:43:07 | MASTER-Kislovodsk | (15h 37m 44.13s , +63d 27m 56.6s) | C | 120 | 17.0 | 6466 | 2025-11-06 21:43:07 | MASTER-Kislovodsk | (15h 37m 27.84s , +63d 05m 06.8s) | C | 120 | 17.0 | 6606 | 2025-11-06 21:45:27 | MASTER-Kislovodsk | (15h 36m 43.61s , +62d 51m 28.9s) | C | 120 | 16.5 | 6606 | 2025-11-06 21:45:27 | MASTER-Kislovodsk | (15h 36m 34.62s , +63d 14m 55.2s) | C | 120 | 16.4 | 6746 | 2025-11-06 21:47:47 | MASTER-Kislovodsk | (15h 36m 43.64s , +62d 52m 15.3s) | C | 120 | 17.0 | 6746 | 2025-11-06 21:47:47 | MASTER-Kislovodsk | (15h 36m 34.72s , +63d 15m 41.8s) | C | 120 | 16.8 | 6886 | 2025-11-06 21:50:07 | MASTER-Kislovodsk | (15h 36m 52.34s , +62d 51m 06.6s) | C | 120 | 17.1 | 6886 | 2025-11-06 21:50:07 | MASTER-Kislovodsk | (15h 36m 43.50s , +63d 14m 32.6s) | C | 120 | 16.9 | 7026 | 2025-11-06 21:52:27 | MASTER-Kislovodsk | (15h 36m 46.55s , +62d 50m 00.4s) | C | 120 | 17.1 | 7026 | 2025-11-06 21:52:27 | MASTER-Kislovodsk | (15h 36m 37.62s , +63d 13m 26.3s) | C | 120 | 16.9 | 7146 | 2025-11-06 21:52:27 | MASTER-Kislovodsk | (15h 36m 37.62s , +63d 13m 26.3s) | C | 360 | 17.6 | Coadd 7166 | 2025-11-06 21:54:47 | MASTER-Kislovodsk | (15h 36m 53.63s , +62d 50m 22.6s) | C | 120 | 17.1 | 7166 | 2025-11-06 21:54:47 | MASTER-Kislovodsk | (15h 36m 44.73s , +63d 13m 48.7s) | C | 120 | 16.9 | 7306 | 2025-11-06 21:57:07 | MASTER-Kislovodsk | (15h 36m 43.81s , +63d 14m 57.1s) | C | 120 | 16.9 | 7306 | 2025-11-06 21:57:07 | MASTER-Kislovodsk | (15h 36m 52.47s , +62d 51m 30.6s) | C | 120 | 17.4 | 7446 | 2025-11-06 21:59:27 | MASTER-Kislovodsk | (15h 36m 53.33s , +62d 50m 03.7s) | C | 120 | 17.4 | 7446 | 2025-11-06 21:59:27 | MASTER-Kislovodsk | (15h 36m 44.93s , +63d 13m 30.7s) | C | 120 | 16.9 | 7506 | 2025-11-06 21:59:27 | MASTER-Kislovodsk | (15h 36m 44.93s , +63d 13m 30.7s) | C | 240 | 17.4 | Coadd 7555 | 2025-11-06 22:01:47 | MASTER-Kislovodsk | (15h 36m 57.12s , +62d 51m 25.2s) | C | 60 | 17.1 | 7555 | 2025-11-06 22:01:47 | MASTER-Kislovodsk | (15h 36m 48.66s , +63d 14m 52.3s) | C | 60 | 16.8 | 7635 | 2025-11-06 22:03:07 | MASTER-Kislovodsk | (15h 36m 50.86s , +62d 50m 51.1s) | C | 60 | 17.1 | 7635 | 2025-11-06 22:03:07 | MASTER-Kislovodsk | (15h 36m 42.49s , +63d 14m 18.3s) | C | 60 | 16.7 | 7715 | 2025-11-06 22:04:26 | MASTER-Kislovodsk | (15h 36m 52.49s , +62d 51m 51.8s) | C | 60 | 17.1 | 7715 | 2025-11-06 22:04:26 | MASTER-Kislovodsk | (15h 36m 44.22s , +63d 15m 18.9s) | C | 60 | 16.7 | 7775 | 2025-11-06 22:04:26 | MASTER-Kislovodsk | (15h 36m 44.21s , +63d 15m 18.9s) | C | 180 | 17.4 | Coadd 7795 | 2025-11-06 22:05:46 | MASTER-Kislovodsk | (15h 36m 50.63s , +63d 14m 18.7s) | C | 60 | 16.8 | 7795 | 2025-11-06 22:05:46 | MASTER-Kislovodsk | (15h 36m 58.82s , +62d 50m 51.4s) | C | 60 | 17.1 | 7874 | 2025-11-06 22:07:05 | MASTER-Kislovodsk | (15h 36m 53.69s , +62d 49m 51.8s) | C | 60 | 17.1 | 7874 | 2025-11-06 22:07:05 | MASTER-Kislovodsk | (15h 36m 45.62s , +63d 13m 19.1s) | C | 60 | 16.6 | 7954 | 2025-11-06 22:08:25 | MASTER-Kislovodsk | (15h 36m 51.15s , +63d 13m 49.4s) | C | 60 | 16.6 | 8014 | 2025-11-06 22:08:25 | MASTER-Kislovodsk | (15h 36m 51.15s , +63d 13m 49.3s) | C | 180 | 17.4 | Coadd 7954 | 2025-11-06 22:08:25 | MASTER-Kislovodsk | (15h 36m 59.17s , +62d 50m 21.8s) | C | 60 | 17.0 | 8034 | 2025-11-06 22:09:45 | MASTER-Kislovodsk | (15h 36m 48.62s , +63d 15m 03.0s) | C | 60 | 16.7 | 8034 | 2025-11-06 22:09:45 | MASTER-Kislovodsk | (15h 36m 56.65s , +62d 51m 35.8s) | C | 60 | 17.1 | 8113 | 2025-11-06 22:11:05 | MASTER-Kislovodsk | (15h 36m 58.21s , +62d 50m 14.3s) | C | 60 | 16.9 | 8113 | 2025-11-06 22:11:05 | MASTER-Kislovodsk | (15h 36m 50.21s , +63d 13m 41.8s) | C | 60 | 16.6 | 8193 | 2025-11-06 22:12:24 | MASTER-Kislovodsk | (15h 36m 53.00s , +63d 15m 14.2s) | C | 60 | 16.6 | 8253 | 2025-11-06 22:12:24 | MASTER-Kislovodsk | (15h 36m 52.99s , +63d 15m 14.2s) | C | 180 | 17.4 | Coadd 8193 | 2025-11-06 22:12:24 | MASTER-Kislovodsk | (15h 37m 00.97s , +62d 51m 46.9s) | C | 60 | 16.9 | 8273 | 2025-11-06 22:13:44 | MASTER-Kislovodsk | (15h 36m 47.55s , +63d 14m 22.9s) | C | 60 | 16.5 | 8273 | 2025-11-06 22:13:44 | MASTER-Kislovodsk | (15h 36m 55.50s , +62d 50m 55.9s) | C | 60 | 16.9 | 8353 | 2025-11-06 22:15:04 | MASTER-Kislovodsk | (15h 36m 47.15s , +63d 15m 23.3s) | C | 60 | 16.5 | 8353 | 2025-11-06 22:15:04 | MASTER-Kislovodsk | (15h 36m 55.10s , +62d 51m 56.7s) | C | 60 | 16.8 | 8433 | 2025-11-06 22:16:24 | MASTER-Kislovodsk | (15h 36m 53.72s , +63d 14m 23.2s) | C | 60 | 16.4 | 8433 | 2025-11-06 22:16:24 | MASTER-Kislovodsk | (15h 37m 01.82s , +62d 50m 56.9s) | C | 60 | 16.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42617. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40679] LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42616 SUBJECT: LIGO/Virgo/KAGRA S251105aj: Updated Sky localization DATE: 25/11/07 17:23:04 GMT FROM: Lorenzo Pompili at Max Planck Institute for Gravitational Physics <lorenzo.pompili(a)aei.mpg.de> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S251105aj (GCN Circular 42587). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S251105aj For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 376 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2483 +/- 735 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/42616. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40678] LIGO/Virgo/KAGRA S251103f: Updated Sky localization
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42615 SUBJECT: LIGO/Virgo/KAGRA S251103f: Updated Sky localization DATE: 25/11/07 17:19:59 GMT FROM: Lorenzo Pompili at Max Planck Institute for Gravitational Physics <lorenzo.pompili(a)aei.mpg.de> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S251103f (GCN Circular 42564). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S251103f For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 757 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2158 +/- 537 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/42615. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40677] IPN triangulation of GRB 251105B (possible sGRB with EE)
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42614 SUBJECT: IPN triangulation of GRB 251105B (possible sGRB with EE) DATE: 25/11/07 15:12:08 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, Y. Zhang, C. Wang, S. Xiong, J. Wei, and B. Cordier on behalf of the SVOM-GRM team, A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns on behalf of the Fermi GBM team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: The possible short-duration GRB with extended emission GRB 251105B (SVOM-GRM detection: Wang et al., GCN 42586; Fermi-GBM detection: Hamburg eat al., GCN 42589; AstroSat-CZTI detection: Harsha et al., GCN 42591) was detected by SVOM (GRM), Konus-Wind, Fermi (GBM), AstroSat (CZTI), and Mars-Odyssey (HEND) at about 3514 s UT (00:58:34). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 277.814 (18h 31m 15s) +9.028 ( +9d 01' 39") Corners: 277.022 (18h 28m 05s) +9.993 ( +9d 59' 36") 277.294 (18h 29m 11s) +9.729 ( +9d 43' 46") 278.607 (18h 34m 26s) +8.012 ( +8d 00' 43") 278.333 (18h 33m 20s) +8.303 ( +8d 18' 10") --------------------------------------------- The error box area is 362 sq. arcmin, and its maximum dimension is 2.5 deg (the minimum one is 3 arcmin). The Sun distance was 62 deg. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB251105_T03511/IPN The HEALPix triangulation map is the multi-order HEALPix in units of probability density. The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. View this GCN Circular online at https://gcn.nasa.gov/circulars/42614. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40676] GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42613 SUBJECT: GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart DATE: 25/11/07 14:32:43 GMT FROM: F. Fortin at IRAP <ffortin.sci.edu(a)gmail.com> Francis Fortin (IRAP), Camila Angulo (UNAM), Jean-Luc Atteia (IRAP), Benjamin Schneider (LAM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the SVOM GRB 251106A (Antier et al., GCN Circ. 42605) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed a second epoch from 2025-11-07 12:34 to 12:50 UTC (from 16.63 to 16.89 hours after the trigger) and obtained an additional 16 minutes of exposure in the r filter at high airmass (3 to 3.5). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We detect the optical counterpart we previously reported (Angulo et al, GCN Circ. 42607) at the following preliminary magnitude: r = 21.85 +/- 0.13 Our photometry shows clear fading with respect to our earlier epoch, confirming that this is the optical counterpart of the GRB. We note that the position of the afterglow optical counterpart is coincident with a faint source in the Legacy Survey (Dey et al. 2019) at r = 22.56 +/- 0.17, which could be the host galaxy of the GRB. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/42613. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40675] GRB 251106B: SVOM/GRM observation of a short burst
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42612 SUBJECT: GRB 251106B: SVOM/GRM observation of a short burst DATE: 25/11/07 10:13:32 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Feliu Lacreu (IAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a burst GRB 251106B (SVOM trigger reference: sb25110603) at 2025-11-06T18:14:44.300 UTC (T0). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple spikes with a T90 of 1.3+0.5/-0.3 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251106B.png The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42612. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40674] GRB 251106A: Swift-XRT afterglow detection
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42611 SUBJECT: GRB 251106A: Swift-XRT afterglow detection DATE: 25/11/07 10:12:12 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), S. Lanava (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAR) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of GRB 251106A. We searched for X-ray sources in 2.0 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 2.0 ks, obtained between T0+4.0 ks and T0+9.9 ks. Three uncatalogued X-ray sources are detected, of which one ("Source 1") is above the RASS 3-sigma upper limit at this position, and is therefore likely the GRB afterglow. Using 2020 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 234.46260, +63.36779 which is equivalent to: RA (J2000): 15h 37m 51.02s Dec(J2000): +63d 22' 04.0" with an uncertainty of 2.6 arcsec (radius, 90% confidence). This position is consistent with the optical afterglow candidate identified by Angulo et al. (GCN 42607). The light curve can be modelled with a power-law decay with a decay index of alpha=0.87 (+0.33, -0.29). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.96 (+0.23, -0.22). The best-fitting absorption column is 1.1 (+0.6, -0.5) x 10^21 cm^-2, in excess of the Galactic value of 1.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.2 x 10^-11 (3.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.1 (+0.6, -0.5) x 10^21 cm^-2 Galactic foreground: 1.7 x 10^20 cm^-2 Excess significance: 2.8 sigma Photon index: 1.96 (+0.23, -0.22) If the light curve continues to decay with a power-law decay index of 0.87, the count rate at T+24 hours will be 0.038 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-12 (1.5 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/03000182. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00048. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42611. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40673] GRB 251106A: Kilonova-Catcher optical upper limit
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42610 SUBJECT: GRB 251106A: Kilonova-Catcher optical upper limit DATE: 25/11/07 08:48:49 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro(a)hotmail.com> M. Freeberg (KNC), D. Turpin (CEA-Saclay/Irfu), C. Andrade(UMN), S. Antier (OCA/IJCLab), M. Coughlin (UMN), S. Karpov (FZU), P. Hello (IJCLAB), M. Pillas (IAP) on behalf of the GRANDMA/Kilonova-Catcher collaboration: We observed the field of GRB 251106A detected by SVOM (Antier et al., GCN 42605), Swift/BAT-GUANO (Delaunay et al., GCN 42608) and Fermi/GBM subthreshold (Godwin et al., GCN 42608) with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with a TEC160FL telescope operated by M. Freeberg. Our observations started at TGRB+5.4hr and were taken with sdss ri filters. In our stacked frames, subtracted from the PanSTARRS DR2 template image, we do not detect the optical counterpart reported by the SVOM/COLIBRI (FM-GFT) (Angulo et al., GCN 42607). We report our follow-up results in the table below: +---------------+-----------+---------+----------------+-------------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | +===============+===========+=========+================+=============+ | 5.77 | 15 x 180s | r (AB) | 19.7 (5 sigma) | TEC160FL | | 6.58 | 15 x 180s | i(AB) | 20.0 (5 sigma) | TEC160FL | +---------------+-----------+---------+----------------+-------------+ All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the sloan filters were calibrated using the PanSTARRS DR1 catalog. We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023). GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42610. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40672] Fermi GBM Sub-Threshold Detection of GRB 251106A
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42609 SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 251106A DATE: 25/11/07 03:05:39 GMT FROM: Matt Godwin <msg0028(a)uah.edu> M. Godwin (UAH) and R. Hamburg (UAH) report on behalf of the Fermi-GBM Team: SVOM/ECLAIRs detected GRB 251106A on 2025-11-06 at 19:56:37 UTC (Antier et al. 2025, GCN 42605). There was no Fermi-GBM onboard trigger around this event time. An automated, blind search for gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified a roughly spatially-consistent candidate at 19:58:18.89 UTC. The GBM Targeted Search [1], the most sensitive coherent search for GRB-like signals in GBM, also identified a transient spatially consistent with GRB 251106A approximately 10 s before the SVOM trigger time. It is detected most significantly ~133 s after the SVOM trigger time on a 4.096 s timescale with a false alarm rate of 3.8e-5 Hz. The event was best-fit using a "normal" GRB spectrum (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3). The Targeted Search localization is consistent with the SVOM/ECLAIRs location. [1] Goldstein et al. 2019 arXiv:1903.12597 View this GCN Circular online at https://gcn.nasa.gov/circulars/42609. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40671] GRB 251106A: Swift/BAT arcminute localization of a burst
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42608 SUBJECT: GRB 251106A: Swift/BAT arcminute localization of a burst DATE: 25/11/07 02:59:54 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Samuele Ronchini (GSSI), Aaron Tohuvavohu (Cosmic Frontier), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 251106A onboard (T0: 2025-11-06T19:56:37 UTC, SVOM/ECLAIRS GCN 42605). In a ground search of a 10 s event file, available due to a subthreshold trigger onboard. The GRB was detected at a S/N of 7.0 in a single 10 s, 15-150 keV image starting at ~T0 + 129 s. The BAT position is RA, Dec = 234.4744, +63.3387 deg which is RA(J2000) = 15h 37m 53.9s Dec(J2000) = +63d 20′ 19.3″ with an estimated uncertainty of 3 arcmin radius. View this GCN Circular online at https://gcn.nasa.gov/circulars/42608. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40670] GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42607 SUBJECT: GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart DATE: 25/11/07 02:38:53 GMT FROM: Camila Angulo Valdez at UNAM <camiangulo(a)astro.unam.mx> Camila Angulo (UNAM), Francis Fortin (IRAP), Jean-Luc Atteia (IRAP), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the SVOM GRB 251106A (Antier et al., GCN Circ. 42605) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-11-07 01:46 to 01:52 UTC (from 5.82 to 5.93 hours after the trigger) and obtained 360 seconds of simultaneous exposure in the r and z filters. The data were analyzed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We detect an uncatalogued source (revealed by image subtraction using PanSTARRS as template) consistent with the XRT 2.6 arcsec error circle (https://www.swift.ac.uk/SVOM/SVOM_FIELD00048/) at RA, DEC = 234.462239, 63.367568 (J2000) and with preliminary magnitudes of: r = 21.49 +/- 0.10 z = 20.77 +/- 0.13 We suggest this is likely to be the optical counterpart of the GRB. Further observations are ongoing. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/42607. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40669] GRB 251106A: MASTER optical observations
by GCN Circulars 06 Nov '25

06 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42606 SUBJECT: GRB 251106A: MASTER optical observations DATE: 25/11/06 22:11:56 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.A. Senik, V.M. Lipunov, A.Kuznetsov, E.Gorbovskoy, G.Antipov, 1P.Balanutsa, I.Panchenko, N. Tiurina, K.Zhirkov, Ya.Kechin, A.Chasovnikov, V.Topolev, D.Vlasenko, Yu. Tselik(Lomonosov MSU, SAI, Moscow), R. Podesta, C.Francile, F. Podesta, E. Gonzalez (OAFA, San Juan Uni.,Argentina); D. Buckley (SAAO, South Africa), O. Gress, N.Budnev, O.Ershova (Irkutsk State University), A. Sosnovskij (CrAO RAS), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), V.M.Pillet, R.Rebolo Lopez (The Instituto de Astrofisica de Canarias, Spain),L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez,J.Martinez,A.R.Corella,L.H.Rodriguez (INAOE, Guillermo Haro Astrophysic Observatory, Mexico) MASTER-Kislovodsk robotic telescope (Global MASTER-Net [1-4], http://observ.pereplet.ru) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of SVOM GRB 251106A (Antier et al. GCN 42605, Ttrigger= 2025-11-06T19:56:37, Tnotice=2025-11-06 20:21:29.84UT) error-box observations 1550 sec after trigger time at 2025-11-06 20:22:27 UT, with upper limit up to 17.9 mag. The observations began 17deg altitude. The sun altitude was -62.3 deg. The galactic latitude b = 45 deg., longitude l = 98 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3034637 There is no optical counterpart withthe following MASTER upper limits upper limits: Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment 1610 | 2025-11-06 20:22:27 | MASTER-Kislovodsk | (15h 37m 28.85s,+63d 06m 03.4s) | P- | 120 | 15.6 | 1750 | 2025-11-06 20:24:47 | MASTER-Kislovodsk | (15h 37m 29.81s,+63d 05m 56.6s) | P- | 120 | 15.6 | 1750 | 2025-11-06 20:24:47 | MASTER-Kislovodsk | (15h 37m 42.69s,+63d 28m 24.2s) | P| | 120 | 17.2 | 1890 | 2025-11-06 20:27:07 | MASTER-Kislovodsk | (15h 37m 30.71s,+63d 05m 51.6s) | P- | 120 | 15.5 | 1890 | 2025-11-06 20:27:07 | MASTER-Kislovodsk | (15h 37m 43.57s,+63d 28m 18.7s) | P| | 120 | 17.3 | 2030 | 2025-11-06 20:29:27 | MASTER-Kislovodsk | (15h 37m 31.56s,+63d 05m 46.7s) | P- | 120 | 15.6 | 2030 | 2025-11-06 20:29:27 | MASTER-Kislovodsk | (15h 37m 44.37s,+63d 28m 13.8s) | P| | 120 | 17.2 | 2140 | 2025-11-06 20:31:47 | MASTER-Kislovodsk | (15h 37m 25.48s,+63d 04m 04.1s) | C | 60 | 17.0 | 2260 | 2025-11-06 20:31:47 | MASTER-Kislovodsk | (15h 37m 25.50s,+63d 04m 04.1s) | C | 300 | 17.5 | Coadd 2140 | 2025-11-06 20:31:47 | MASTER-Kislovodsk | (15h 37m 38.06s,+63d 26m 36.1s) | C | 60 | 17.4 | 2858 | 2025-11-06 20:43:45 | MASTER-Kislovodsk | (15h 36m 59.84s,+63d 06m 24.9s) | C | 60 | 17.0 | 2918 | 2025-11-06 20:43:45 | MASTER-Kislovodsk | (15h 36m 59.83s,+63d 06m 24.9s) | C | 180 | 17.8 | Coadd 2858 | 2025-11-06 20:43:45 | MASTER-Kislovodsk | (15h 37m 12.09s,+63d 29m 02.0s) | C | 60 | 17.4 | 2938 | 2025-11-06 20:45:05 | MASTER-Kislovodsk | (15h 37m 04.06s,+63d 05m 20.5s) | C | 60 | 17.1 | 2938 | 2025-11-06 20:45:05 | MASTER-Kislovodsk | (15h 37m 16.46s,+63d 27m 56.8s) | C | 60 | 17.5 | 3018 | 2025-11-06 20:46:25 | MASTER-Kislovodsk | (15h 36m 58.81s,+63d 04m 17.3s) | C | 60 | 17.0 | 3018 | 2025-11-06 20:46:25 | MASTER-Kislovodsk | (15h 37m 11.34s,+63d 26m 52.9s) | C | 60 | 17.4 | 3128 | 2025-11-06 20:47:45 | MASTER-Kislovodsk | (15h 37m 04.62s,+63d 04m 30.1s) | C | 120 | 17.3 | 3128 | 2025-11-06 20:47:45 | MASTER-Kislovodsk | (15h 37m 17.42s,+63d 27m 05.1s) | C | 120 | 17.4 | 3289 | 2025-11-06 20:50:26 | MASTER-Kislovodsk | (15h 37m 04.51s,+63d 05m 55.6s) | C | 120 | 17.3 | 3289 | 2025-11-06 20:50:26 | MASTER-Kislovodsk | (15h 37m 17.54s,+63d 28m 30.4s) | C | 120 | 17.5 | 3429 | 2025-11-06 20:52:46 | MASTER-Kislovodsk | (15h 37m 05.48s,+63d 04m 10.8s) | C | 120 | 17.2 | 3549 | 2025-11-06 20:52:46 | MASTER-Kislovodsk | (15h 37m 05.48s,+63d 04m 10.8s) | C | 360 | 17.9 | Coadd 3429 | 2025-11-06 20:52:46 | MASTER-Kislovodsk | (15h 37m 18.70s,+63d 26m 45.1s) | C | 120 | 17.5 | 3569 | 2025-11-06 20:55:05 | MASTER-Kislovodsk | (15h 37m 07.60s,+63d 05m 54.6s) | C | 120 | 17.2 | 3569 | 2025-11-06 20:55:05 | MASTER-Kislovodsk | (15h 37m 20.97s,+63d 28m 28.6s) | C | 120 | 17.4 | 3709 | 2025-11-06 20:57:25 | MASTER-Kislovodsk | (15h 37m 04.73s,+63d 05m 01.2s) | C | 120 | 17.2 | 3709 | 2025-11-06 20:57:26 | MASTER-Kislovodsk | (15h 37m 18.15s,+63d 27m 35.0s) | C | 120 | 17.4 | 3849 | 2025-11-06 20:59:45 | MASTER-Kislovodsk | (15h 37m 04.57s,+63d 05m 58.7s) | C | 120 | 17.1 | 3909 | 2025-11-06 20:59:45 | MASTER-Kislovodsk | (15h 37m 04.57s,+63d 05m 58.8s) | C | 240 | 17.5 | Coadd 3849 | 2025-11-06 20:59:45 | MASTER-Kislovodsk | (15h 37m 18.12s,+63d 28m 32.3s) | C | 120 | 17.4 | 3959 | 2025-11-06 21:02:05 | MASTER-Kislovodsk | (15h 37m 10.31s,+63d 04m 57.0s) | C | 60 | 16.8 | 3959 | 2025-11-06 21:02:05 | MASTER-Kislovodsk | (15h 37m 23.89s,+63d 27m 30.6s) | C | 60 | 17.2 | 4039 | 2025-11-06 21:03:25 | MASTER-Kislovodsk | (15h 37m 05.87s,+63d 03m 55.5s) | C | 60 | 16.8 | 4039 | 2025-11-06 21:03:25 | MASTER-Kislovodsk | (15h 37m 19.52s,+63d 26m 29.2s) | C | 60 | 17.2 | 4118 | 2025-11-06 21:04:45 | MASTER-Kislovodsk | (15h 37m 13.13s,+63d 04m 18.9s) | C | 60 | 16.8 | 4178 | 2025-11-06 21:04:45 | MASTER-Kislovodsk | (15h 37m 13.12s,+63d 04m 18.9s) | C | 180 | 17.3 | Coadd 4118 | 2025-11-06 21:04:45 | MASTER-Kislovodsk | (15h 37m 26.81s,+63d 26m 52.7s) | C | 60 | 17.1 | Observations and data analysis will be continued. [1] Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L [2] Lipunov et al. 2022, Universe, Vol. 8(5), id.271 [3] Lipunov et a. 2019, ARep, vol.63, 293 [4] Lipunov V., Kornilov V., Gorbovskoy E., Tiurina N., Kuznetsov A. 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics,Lomonosov MSU PRESS, 591pp. http://www.pereplet.ru/lipunov/625.html#625 View this GCN Circular online at https://gcn.nasa.gov/circulars/42606. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40668] GRB 251106A: SVOM detection of a burst
by GCN Circulars 06 Nov '25

06 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42605 SUBJECT: GRB 251106A: SVOM detection of a burst DATE: 25/11/06 20:37:09 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> S. Antier (IJCLAB), M. Dennefeld (IAP), S. Schanne (CEA/Irfu), F. Lacreu (IAP) report on behalf of the SVOM mission team: At 2025-11-06T19:56:37 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251106A (SVOM burst-id sb25110604). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 16 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 11.02 in the [8-120] keV energy band over a time window of 163.84 seconds starting at 2025-11-06T19:55:40. The localization of the best alert is R.A., Dec. 234.6169, 63.3716 degrees: R.A. (J2000) = 15h38m28.05s Dec. (J2000) = 63d22m17.83s with a 90% confidence level (C.L.) radius of 7.27 arcmin (including systematic error of 2 arcmin added in quadrature). Due to sun constraints, no immediate slew was performed on this burst. No X-ray observation could be performed by SVOM/MXT for the time being. No optical observation could be performed by SVOM/VT for the time being. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Sarah Antier: sarah.antier(a)ijclab.in2p3.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42605. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40667] GRB 251103B: AstroSat CZTI detection
by GCN Circulars 06 Nov '25

06 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42604 SUBJECT: GRB 251103B: AstroSat CZTI detection DATE: 25/11/06 19:18:43 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Goyal (IITB), A. Arya (IITB), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 251103B which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42555), and Swift BAT (Lanava et. al., GCN Circ. 42556). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-11-03 16:46:36.50 UTC. The measured peak count rate associated with the burst is 87 (+31, -16) counts/s above the background in the combined data of three quadrants (out of four), with a total of 307 (+118, -98) counts. We caution that there is a 0.3 s readout dead time in CZT data during the burst which affects the calculated total counts. The local mean background count rate was 215 (+2, -4) counts/s. Using cumulative rates, we measure a T90 of 5.86 (+0.85, -2.24) s. The source was also faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-03 16:46:41.66 UTC. The measured peak count rate associated with the burst is 148 (+74, -23) counts/s above the background in the combined data of all quadrants, with a total of 677 (+244, -247) counts. The local mean background count rate was 1281 (+6, -7) counts/s. Due to poor statistics, we cannot reliably estimate the T90 from it. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42604. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40666] GRB 251025C: TERI Gamma-ray detection
by GCN Circulars 06 Nov '25

06 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42603 SUBJECT: GRB 251025C: TERI Gamma-ray detection DATE: 25/11/06 17:23:20 GMT FROM: Daniel Shy <danielshy(a)danielshy.com> Daniel Shy (a), C.C. Cheung (a), Bernard Phlips (a), Michael Streicher (b), James Mason (b), Douglas M. Groves (b), Feng Zhang (b), and Willy Kaye (b) (a) U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (b) H3D, Inc., 812 Avis Dr., Ann Arbor, MI 48108, USA The cadmium zinc TElluride Radiation Imager (TERI) gamma-ray telescope [1], operating on the International Space Station, reports the detection of GRB 251025C, which was also detected by Fermi/GBM (GCN 42449), CALET (GCN 42467), AstroSat CZTI (GCN 42469), and Glowbug (GCN 42490). Using 1 Hz binning, we observe a single peak at 2025-10-25T23:08:40.79 with an excess of 27 counts per second (cps) above the 39 cps baseline rate observed in nearby off-source intervals. The analysis results presented here are preliminary and currently lack a detailed response function. TERI is an Office of Naval Research funded technology demonstrator for large-volume pixelated CdZnTe detectors developed, built, and operated by the U.S. Naval Research Laboratory (NRL) in conjunction with H3D, Inc. The pixelated CdZnTe detectors have an energy range of 40 keV to 3 MeV per pixel. It was launched on 2025 April 21 aboard the Department of Defense Space Test Program’s STP-H10 to the ISS. On the ISS, it is located on the SOX external payload facility on the Columbus module. Analysis of TERI data at NRL is supported under contract with NASA as correlative science for the Fermi Gamma-ray Space Telescope. [1] Shy, Daniel, et al. "Development of the cadmium zinc TElluride Radiation Imager." Journal of Astronomical Telescopes, Instruments, and Systems 10.4 (2024): 044009-044009 (arXiv:2408.04559). Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42603. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40665] GRB 251016B: TERI Gamma-ray detection
by GCN Circulars 06 Nov '25

06 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42602 SUBJECT: GRB 251016B: TERI Gamma-ray detection DATE: 25/11/06 17:21:27 GMT FROM: Daniel Shy <danielshy(a)danielshy.com> Daniel Shy (a), C.C. Cheung (a), Bernard Phlips (a), Michael Streicher (b), James Mason (b), Douglas M. Groves (b), Feng Zhang (b), and Willy Kaye (b) (a) U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (b) H3D, Inc., 812 Avis Dr., Ann Arbor, MI 48108, USA The cadmium zinc TElluride Radiation Imager (TERI) gamma-ray telescope [1], operating on the International Space Station, reports the detection of GRB 251016B, which was also detected by Fermi/GBM (GCN 42316, 42383), CALET (GCN 42320), AstroSat/CZTI (GCN 42324), IPN triangulation (GCN 42403), Konus-Wind (GCN 42448) Using 1 Hz binning, and adopting T0 = 2025-10-16T23:59:00.72, we observe a single peak at T0+2.5s with an excess of 83 counts per second (cps) above the 39 cps baseline rate observed in nearby off-source intervals. The analysis results presented here are preliminary and currently lack a detailed response function. TERI is an Office of Naval Research funded technology demonstrator for large-volume pixelated CdZnTe detectors developed, built, and operated by the U.S. Naval Research Laboratory (NRL) in conjunction with H3D, Inc. The pixelated CdZnTe detectors have an energy range of 40 keV to 3 MeV per pixel. It was launched on 2025 April 21 aboard the Department of Defense Space Test Program’s STP-H10 to the ISS. On the ISS, it is located on the SOX external payload facility on the Columbus module. Analysis of TERI data at NRL is supported under contract with NASA as correlative science for the Fermi Gamma-ray Space Telescope. [1] Shy, Daniel, et al. "Development of the cadmium zinc TElluride Radiation Imager." Journal of Astronomical Telescopes, Instruments, and Systems 10.4 (2024): 044009-044009 (arXiv:2408.04559). Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42602. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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