November 2025 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 40892] GRB 251121B: Fermi GBM Final Localization
by GCN Circulars 24 Nov '25

24 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42823 SUBJECT: GRB 251121B: Fermi GBM Final Localization DATE: 25/11/24 16:55:01 GMT FROM: atrigg2(a)lsu.edu The Fermi GBM team reports the detection of a likely SHORT GRB "At 23:44:26.90 UT on 22 November 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251121B (trigger 785547871/251122989). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 336.52, Dec = -55.63 (J2000 degrees, equivalent to J2000 22h 26m, -55d 38'), with a statistical uncertainty of 10.74 degrees. The angle from the Fermi LAT boresight is 36.00 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251122989/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251122989/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251122989/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/42823. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40891] EP251118A: 6 GHz VLA Detection
by GCN Circulars 24 Nov '25

24 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42822 SUBJECT: EP251118A: 6 GHz VLA Detection DATE: 25/11/24 15:40:05 GMT FROM: muskan.yadav(a)students.uniroma2.eu Muskan Yadav, Roberto Ricci, Eleonora Troja (U Rome) report: We observed the position of EP251118A (Jiang et al., GCN 42749; Malesani et al., GCN 42751) with the Karl G. Jansky Very Large Array (VLA) on 2025 November 20, starting at 13:52 UT (~1.88 days after the EP/WXT trigger), at a central frequency of 6 GHz. In our preliminary analysis, we detect a radio counterpart at 6 GHz with a flux density of ∼74 μJy. The position is consistent with the optical counterpart (An et al., GCN 42756; Belkin et al., GCN 42758; Yadav et al., GCN 42760; Busmann et al., GCN 42763; Francile et al., GCN 42767; Urquijo-Rodríguez et al., GCN 42773; Lee et al., GCN 42780; Li et al., GCN 42776; Liu et al., GCN 42793; Moskvitin et al., GCN 42785; Aryan et al., GCN 42798; Gupta et al., GCN 42787) and the X-ray counterpart (Shi et al., GCN 42754). We thank the VLA staff for rapidly executing these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42822. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40890] Fermi GRB 251124a: Global MASTER-Net observations report
by GCN Circulars 24 Nov '25

24 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42821 SUBJECT: Fermi GRB 251124a: Global MASTER-Net observations report DATE: 25/11/24 15:30:22 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 GRB 251124a ( Fermi GBM team, GCN 42820) errorbox 5857 sec after notice time and 5878 sec after trigger time at 2025-11-24 14:36:01 UT, with upper limit up to 13.0 mag. Observations started at twilight. The observations began at zenith distance = 62 deg. The sun altitude is -10.2 deg. The galactic latitude b = 29 deg., longitude l = 38 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3050796 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 5938 | 2025-11-24 14:36:01 | MASTER-Kislovodsk | (17h 11m 31.23s , +16d 54m 33.8s) | P- | 120 | 12.6 | 6078 | 2025-11-24 14:38:21 | MASTER-Kislovodsk | (17h 11m 31.15s , +16d 54m 22.6s) | P- | 120 | 12.5 | 6218 | 2025-11-24 14:40:41 | MASTER-Kislovodsk | (17h 11m 32.20s , +17d 16m 49.8s) | P| | 120 | 12.2 | 6218 | 2025-11-24 14:40:41 | MASTER-Kislovodsk | (17h 11m 31.11s , +16d 54m 13.1s) | P- | 120 | 13.0 | 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/42821. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40889] GRB 251124a: Fermi GBM Final Localization
by GCN Circulars 24 Nov '25

24 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42820 SUBJECT: GRB 251124a: Fermi GBM Final Localization DATE: 25/11/24 15:09:47 GMT FROM: Andreas von Kienlin at MPE <azk(a)mpe.mpg.de> The Fermi GBM team reports the detection of a LONG GRB "At 12:58:03.47 UT on 24 November 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251124a (trigger 785681888/251124540). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 258.14, Dec = 16.86 (J2000 degrees, equivalent to J2000 17h 12m, +16d 51'), with a statistical uncertainty of 1.00 degrees. The angle from the Fermi LAT boresight is 63 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251124540/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251124540/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251124540/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/42820. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40888] LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
by GCN Circulars 24 Nov '25

24 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42819 SUBJECT: LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901 DATE: 25/11/24 15:06:20 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), H. Yang, O. Godet, J.-L. Atteia, M. Brunet, S. Guillot (IRAP), M. Pillas (IAP) report on behalf of the SVOM/VT team. SVOM/VT performed a Target of Opportunity observation of the high-energy transient SVOM J2320.0-2901 detected by SVOM/ECLAIRs (Yang et al., GCN 42797), right after S251105aj reported by LIGO/Virgo/KAGRA (The LIGO-Virgo-Kagra Collaboration, GCN 42587; GCN 42616). The observation began at 2025-11-16T00:47:45 UT, 10.5 days after SVOM/ECLAIRs detection, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The VT field of view covered 96% of the 90% C.L. ECLAIRs error region, but no uncataloged sources were detected within the error box of ECL. VT also covered three EP/FXT sources (source#1: RA, Dec = 349.8643, -29.0602 deg; source#2: 350.1419, -29.0148 deg; source#3: 349.9737, -28.8522 deg) reported by Guillot et al. (GCN 42818). None of the known sources became apparent brighter within errorbox of three FXT candidates compared with Legacy Survey DR10. The 3 sigma upper limit was VT_R > 23.6 mag and VT_B > 23.8 mag with the exposure time of 65*70 sec. Further analysis is ongoing. 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/42819. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40887] LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
by GCN Circulars 24 Nov '25

24 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42818 SUBJECT: LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901 DATE: 25/11/24 15:05:57 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> S. Guillot, H. Yang, O. Godet, J.-L. Atteia (IRAP), M. Pillas (IAP), L. P. Xin, Y. N. Ma, H. W. Pan, T. Zhao (NAOC), Y. J. Yi, A. Li (BNU), R. X. Hu (WHU), D. Z. Du (ZJU), C. Y. Wang (THU) on behalf of the Einstein Probe (EP) team: EP-FXT performed a Target of Opportunity observation of the high-energy transient SVOM J2320.0-2901 detected by SVOM/ECLAIRs (Yang et al., GCN 42797), in a search for possible counterparts of the compact binary merger candidate S251105aj (The LIGO-Virgo-Kagra Collaboration, GCN 42587). The observation was conducted at 2025-11-15T21:39:22 UTC with an exposure of 5 ks, about 10.36 days after the GW trigger and the detection time of SVOM J2320.0-2901. EP-FXT covered the full area of the 90% C.L. ECLAIRs error region and detected six sources above a SNR of 4.5 within 15 arcminutes from SVOM J2320.0-2901. Their information is summarized below (RA/Dec in degrees with 10" error radius (90% C.L.); fluxes are the observed ones in 0.5–10 keV): # | Name | RA | Dec | Flux (erg/s/cm^2) | SNR —---------------------------------------------------------------------------------------------------- 1 | EPF_J231927.4-290337 | 349.8643 | -29.0602 | 1.4e-13 | 4.7 2 | EPF_J232034.0-290053 | 350.1419 | -29.0148 | 2.2e-13 | 10.0 3 | EPF_J231953.7-285108 | 349.9737 | -28.8522 | 1.7e-13 | 5.7 4 | EPF_J231906.2-290806 | 349.7760 | -29.1351 | 3.4e-13 | 5.8 5 | EPF_J232051.4-285356 | 350.2140 | -28.8990 | 2.4e-13 | 8.4 6 | EPF_J232108.1-290032 | 350.2839 | -29.0088 | 2.6e-13 | 7.9 We cross-matched all six FXT detections against the SIMBAD, NED, and Vizier catalogues, using a 20″ matching radius (for a galaxy at 2000 Mpc, this corresponds to an offset of ~200 kpc). Five FXT detections (#2,3,4,5,6) are matched to five optical quasars correspondingly, with their redshifts in a range of 0.721 to 1.641, higher than z=0.374 estimated for the GW event. The remaining source (#1) is matched to a source from the KiDSDR4 QSOs photometric redshifts catalog (Nakoneczny et al., 2021), which is classified as a quasar with 68% probability and a photometric redshift of 0.5 +/- 1.2 based on machine learning estimates. We conducted SVOM/VT on this field with the results reported in GCN 42819. Further FXT observations of these candidates will be conducted. 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/42818. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40886] EP251124a: GROWTH-India Telescope optical upper limits
by GCN Circulars 24 Nov '25

24 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42817 SUBJECT: EP251124a: GROWTH-India Telescope optical upper limits DATE: 25/11/24 15:02:41 GMT FROM: V. Swain at IIT Bombay <vishwajeet.s(a)iitb.ac.in> T. Mohan (IITB), S. Patil (IITB), D. Eappachen (IIA), V.Swain (IITB), A.P. Saikia (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team: We observed the field of EP transient (Zhou et al., GCN 42816), with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2025-11-24T13:25:59 UT, i.e., about 2.27 hours after the EP-WXT trigger. Two exposures were obtained each in r' and g' filters. We did not detect any transient in our images within the WXT localization region and at the position of FXT sources - FXTA, FXTB1, and FXTB2. The photometric upper limits are as follows: | MJD (mid) | Filter | tmid-t0 (min) | Exposure Time (sec) | Upper limit (AB) | | ------------ | ------ | ------------- | ------------------- | ---------------- | | 61003.55971 | r' | 135.9 | 300 | 20.5 | | 61003.56539 | g' | 144.1 | 300 | 20.8 | The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction. The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/. View this GCN Circular online at https://gcn.nasa.gov/circulars/42817. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40885] EP251124a: Einstein Probe detection of an X-ray transient
by GCN Circulars 24 Nov '25

24 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42816 SUBJECT: EP251124a: Einstein Probe detection of an X-ray transient DATE: 25/11/24 13:17:56 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> H.Zhou (PMO, CAS), J. -Y. Cao (IHEP), H.-N. Yang, and Z.-X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP251124a. The transient triggered EP-WXT (ID: 01709248862) at 2025-11-24T11:10:05 (UTC). The WXT position of the source is R.A. = 43.732 deg, DEC = 41.577 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. According to the FXT onboard alert, which provided coordinates calculated autonomously on board the satellite, FXTA detected an X-ray source and FXTB detected two X-ray sources (denoted as FXTB-1 and FXTB-2) within the WXT error circle. Their coordinates (J2000) are: FXTA: R.A. = 43.7117 deg, DEC = 41.5715 deg FXTB-1: R.A. = 43.7188 deg, DEC = 41.5692 deg FXTB-2: R.A. = 43.7061 deg, DEC = 41.6121 deg All FXT localizations are reported with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). FXTB-1 is consistent with the source detected by FXTA. Further information will be updated when the telemetry data is received. 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/42816. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40884] GRB 251116C: Swift-XRT confirmation of fading
by GCN Circulars 24 Nov '25

24 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42815 SUBJECT: GRB 251116C: Swift-XRT confirmation of fading DATE: 25/11/24 10:30:46 GMT FROM: Matteo Ferro at INAF-OAB <matteo.ferro(a)inaf.it> M. Ferro, M. G. Bernardini, B. Sbarufatti, C. Salvaggio, R. Brivio, A. Mei (INAF-OAB) report on behalf of the Swift-XRT team: Swift-XRT has conducted further observations of the field of the SVOM/ECLAIRs-detected burst GRB 251116C (Pillas et al., GCN 42703). The observations now extend from T0+10 ks to T0+452 ks and have a total exposure time of 6.1 ks. The previously-reported "Source 1" (Evans et al., GCN 42721), is now found to be fading with ~3-sigma significance, and is therefore likely the GRB afterglow. The results of the XRT-team automatic analysis of the source are available at https://www.swift.ac.uk/SVOM/team/SVOM_FIELD00051/Source1.php. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00051/. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42815. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40883] GRB 251122A/EP251122a: FTW optical and NIR observations
by GCN Circulars 23 Nov '25

23 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42814 SUBJECT: GRB 251122A/EP251122a: FTW optical and NIR observations DATE: 25/11/23 22:37:25 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann(a)physik.lmu.de> Malte Busmann (LMU), Xander J. Hall (CMU), Brendan O’Connor (CMU), Daniel Gruen (LMU), and Antonella Palmese (CMU) report: We observed the FXT localization of GRB 251122A/EP251122a (Wang et al., GCN 42779; Lin et al., GCN 42800; Yin et al., GCN 42808; Wang et al., GCN 42809) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i, and J bands simultaneously for 40 x 180 s starting at 2025-11-23T00:06:12 UT (0.43 days after the trigger). We used r-band templates from the DESI Legacy Survey for difference imaging and did not detect the source identified by Cheng et al. (GCN 42803), Li et al. (GCN 42806), Sun et al. (GCN 42807), Ma et al. (GCN 42811), and Gupta et al. (GCN 42813) at a 3-sigma depth of r > 24 AB mag. The magnitude is calibrated against the PS1 catalog and not corrected for Galactic extinction. We thank Christoph Ries from the Wendelstein Observatory for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42814. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0