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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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