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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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