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

[vsnet-grb-info 40641] GRB 251103B: Fermi GBM observation
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42582 SUBJECT: GRB 251103B: Fermi GBM observation DATE: 25/11/04 21:18:14 GMT FROM: atrigg2(a)lsu.edu A. C. Trigg (NPP, NASA MSFC) report on behalf of the Fermi GBM Team: "At 16:46:36.44 UT on 03 November 2025, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 251103B (trigger 783881201/251103699), which was also detected by the Swift/XRT (Evans et al. 2025, GCN 42557) The Fermi GBM Final Real-time Localization (GCN 42555) is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 70 degrees. The GBM light curve shows/consists of rapid multi-peaked emission with a duration (T90) of about 15 s (50-300 keV). The time-averaged spectrum from T0-0.00 s to T0+10.0 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.07 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 149 +/- 3 keV. The event fluence (10-1000 keV) in this time interval is (2.28 +/- 0.08)E-6 erg/cm^2. The 256-msec peak photon flux measured starting from T0+2.24 s in the 10-1000 keV band is 5.6 +/- 0.5 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak= 146 +/- 3 keV, alpha = -1.07 +/- 0.01, and beta = -3.3 +/- 0.06. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/42582. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40640] GRB 251104A: SVOM detection of a burst
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42581 SUBJECT: GRB 251104A: SVOM detection of a burst DATE: 25/11/04 17:59:48 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M.G. Bernardini (INAF-OAB, LUPM), M. Pillas (IAP), N. Dagoneau (CEA), F. Lacreu (IAP) At 2025-11-04T17:30:58 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251104A (SVOM burst-id sb25110404). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Image Trigger (IMT), which produced a sequence of 6 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 10.82 in the [5-8] keV energy band over a time window of 655.36 seconds starting at 2025-11-04T17:28:14. The localization of the best alert is R.A., Dec. 26.5099, 15.5077 degrees: R.A. (J2000) = 1h46m02.39s Dec. (J2000) = 15d30m27.56s with a 90% confidence level (C.L.) radius of 7.39 arcmin (including systematic error of 2 arcmin added in quadrature). 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 Maria Grazia Bernardini: maria.bernardini(a)inaf.it. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42581. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40639] GRB 251013C: 7DT detection and Medium-band SED of Afterglow
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42569 SUBJECT: GRB 251013C: 7DT detection and Medium-band SED of Afterglow DATE: 25/11/04 06:14:11 GMT FROM: YoungPyo Hong at Seoul National University <evan77333(a)gmail.com> YoungPyo Hong (SNU ARC/SNU), Donggeun Tak (SNU ARC/SNU), Myungshin Im (SNU ARC/SNU), Hyeonho Choi (SNU ARC/SNU), Seo-Won Chang (SNU ARC/SNU), and Ji Hoon Kim (SNU ARC/SNU) report on behalf of the 7-Dimensional Sky Survey team: At 2025-10-14T00:02:30 UTC (about 6 hours after the GRB), we observed the optical counterpart of GRB 251013C (Fermi GBM team GCN 42221, Rakotondrainibe et al. GCN 42222), first reported by SVOM/VT (Palmerio et al. GCN 42223) using 7-Dimensional Telescope (7DT) at the El Sauce Observatory in Chile. Observations were made with 10 7DT units in g, r, i-band and 14 medium-band filters, in which the numeric values indicate their central wavelengths in nanometers. Each medium-band filter has a bandwidth of 25nm. The counterpart was detected at the following position: RA(J2000) = 345.8356 (deg) / 23h03m20.54s RA(J2000) = -0.2103 (deg) / -00°12'37.08" We report our photometry result with 14 medium-band and g, r, i band filters: Filter Mag Mag_err Exposure Date Time T-T0 --------------------------------------------------------------------------------------------------- g 18.11 0.02 3x100s 2025-10-14T00:06:00 6:15:48 r 17.77 0.02 3x100s 2025-10-14T00:12:58 6:22:46 i 17.55 0.05 3x100s 2025-10-14T00:06:10 6:15:59 m400 18.34 0.08 3x100s 2025-10-14T00:12:53 6:22:42 m425 18.29 0.05 3x100s 2025-10-14T00:13:00 6:22:49 m450 18.00 0.04 3x100s 2025-10-14T00:05:55 6:15:43 m475 18.04 0.03 3x100s 2025-10-14T00:12:53 6:22:42 m500 18.07 0.04 3x100s 2025-10-14T00:13:40 6:23:28 m525 17.98 0.04 3x100s 2025-10-14T00:12:54 6:22:43 m550 17.88 0.04 3x100s 2025-10-14T00:13:00 6:22:49 m575 17.85 0.05 3x100s 2025-10-14T00:06:19 6:16:07 m600 17.86 0.07 3x100s 2025-10-14T00:06:16 6:16:05 m625 17.64 0.08 3x100s 2025-10-14T00:06:03 6:15:52 m650 17.57 0.07 3x100s 2025-10-14T00:05:54 6:15:42 m675 17.73 0.05 3x100s 2025-10-14T00:13:29 6:23:17 m700 17.58 0.06 3x100s 2025-10-14T00:05:57 6:15:46 m750 17.41 0.09 3x100s 2025-10-14T00:05:51 6:15:40 m750 17.36 0.08 3x100s 2025-10-14T00:13:41 6:23:30 Photometric flux calibration was performed using synthetic photometry based on the Gaia DR3 XP catalog (Gaia Collaboration et al. 2022) within the AB magnitude system. This is based on preliminary photometry, and no extinction correction has been applied. The 7-Dimensional Telescope (7DT), located in Chile and comprising 20 wide-field telescopes equipped with 40 medium-bandwidth (~25nm) filters, aims to detect optical counterparts of GW sources and conduct the 7-Dimensional Sky Survey (7DS) of the Southern Hemisphere. Further information about the 7DT is available at [http://7ds.snu.ac.kr/](http://7ds.snu.ac.kr/). View this GCN Circular online at https://gcn.nasa.gov/circulars/42569. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40638] GRB 251028A: Insight-HXMT/HE detection
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42580 SUBJECT: GRB 251028A: Insight-HXMT/HE detection DATE: 25/11/04 15:24:23 GMT FROM: guohx(a)ihep.ac.cn Hao-Xuan Guo, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng (IHEP) report on behalf of the Insight-HXMT team: At 2025-10-28T03:26:40.000 (T0), Insight-HXMT/HE detected a long burst, GRB 251028A, which is also detected by Fermi/GBM (Fermi GBM team, GCN#42497, GCN#42499), MAXI/GSC (MAXI team, GCN#42498), Glowbug (C.C. Cheung et al., GCN#42506), SVOM/GRM (SVOM/GRM team, SVOM/ECLAIRs team, GCN#42522), GECAM-B (GECAM team, GCN#42523), and Konus-Wind (Konus-Wind team, GCN#42527). The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 80 +21/-30 s. The 1s peak rate, measured from T0-4.5 s, is 450 cnts/sec. Insight-HXMT/HE detected a total of 9154 counts from this burst. The Insight-HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251028A.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/42580. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40637] GRB 251103A: Optical afterglow detection by ZTF’s public survey
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42579 SUBJECT: GRB 251103A: Optical afterglow detection by ZTF’s public survey DATE: 25/11/04 15:14:43 GMT FROM: Amaliya Atamalibekova <aa2569(a)cornell.edu> A. Atamalibekova and A. Y. Q. Ho (Cornell) We report a serendipitous detection of the optical afterglow to GRB 251103A (Hu et al., GCN 42534, Schneider et al., GCN Circ. 42535; Turpin et al., GCN Circ. 42538; Gritsevich et al., GCN Circ. 42539; Izzo et al., GCN Circ. 42540, O'Neill et al., GCN Circ. 42543, Ghosh et al., GCN Circ. 42545, A. A. Breeveld et al., GCN Circ. 42554, R. Hellot et al., GCN Circ. 42559) by the Zwicky Transient Facility Public Survey. The transient ZTF25accpzjo was detected on 2025-11-03 22:39 UTC at g=19.76 +/- 0.21 mag, and two hours later at r = 19.24 +/- 0.11 mag. The last upper limit was two days prior, at 2025-11-01 23:56 UTC (g > 21.10 mag from forced photometry). The combination of fast rise (0.67 mag/day) and red colors g-r = 0.47 +/- 0.23 (corrected for Milky Way extinction) was flagged by a pipeline for discovering afterglows in the ZTF data (e.g. Ho et al. 2020, ApJ, 905, 98). Upon a retrospective search, we identified ZTF25accpzjo as the afterglow to GRB 251103A. View this GCN Circular online at https://gcn.nasa.gov/circulars/42579. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40636] EP251102a: FTW optical and NIR observations
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42578 SUBJECT: EP251102a: FTW optical and NIR observations DATE: 25/11/04 13:49:28 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann(a)physik.lmu.de> Malte Busmann, Rasika Deshpande (LMU), Xander Hall, Brendan O’Connor (Carnegie Mellon U.), Daniel Gruen (LMU), and Antonella Palmese (Carnegie Mellon U.) report: We observed the counterpart of EP251102a (Schneider et al., GCN 42544; Eyles-Ferris et al., GCN 42546; Liang et al., GCN 42548; Mo et al., GCN 42563; Adami et al., GCN 42575) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i, and J bands simultaneously for 7 x 180 s starting at 2025-11-04T04:50:46 UT (0.94 days after the trigger). We detect the counterpart in all bands and report the following magnitude: r = (21.02 +/- 0.06) AB mag The magnitude is calibrated against the PS1 catalog and not corrected for Galactic extinction. We thank Christoph Ries for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42578. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40635] GRB 251103A: WFST optical observations
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42577 SUBJECT: GRB 251103A: WFST optical observations DATE: 25/11/04 13:13:47 GMT FROM: ylhua(a)pmo.ac.cn Yan-Long Hua, Chao Wu (NAOC), Jin-Jun Geng, Xue-Feng Wu, Jun-Jie Wei, Tian-Rui Sun, Yi-Fang Liang, Ding-Fang Hu, Guan-Xiao Li, Yuan-Tai Yang, Jia-Zheng Zhu, Ze-Lin Xu, Ning Jiang, Ji-An Jiang report on behalf of the WFST team: Following the detection of GRB 251103A by SVOM(Hu et al., GCN 42534，Benjamin Schneider et al., GCN 42549,Chen-Wei Wang et al., GCN 42552), Fermi/GBM (Fermi GBM Team, GCN 42536, GCN 42553), Swift (J.P. Osborne et al., GCN 42551,A. A. Breeveld et al., GCN 42554). We performed follow-up observations using the Wide Field Survey Telescope (WFST Collaboration; arXiv:2306.07590) at the Lenghu Astronomical Observation Base in Qinghai Province, China. Observations in the r/g band began at 2025-11-03T20:57:29 UTC, approximately 16 hours after the trigger. The afterglow is detected in r/g band we measured the following preliminary magnitude: r = 20.82 +/- 0.16,2025-11-03T20:59:45 UTC g = 21.10 +/- 0.12,2025-11-03T22:30:38 UTC The photometric calibration was performed using nearby stars from the PanSTARRS catalog is in the AB system, and is not corrected for Galactic extinction. We thank the WFST staff for supporting these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42577. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40634] EP251102a: update of EP-FXT follow-up observation
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42576 SUBJECT: EP251102a: update of EP-FXT follow-up observation DATE: 25/11/04 13:08:10 GMT FROM: Hao Zhou at Purple Mountain Observatory, CAS <haozhou(a)pmo.ac.cn> H. Zhou, Y.-F. Liang (PMO, CAS) and H.-W. Pan (NAO, CAS) report on behalf of the Einstein Probe team: The Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) performed one ToO observation for EP251102a, starting at 2025-11-03T11:21:51 (UTC) with an exposure time of about 2.1 ks. The ground-processed position of EP251102a is R.A. = 113.1622 deg, DEC = 7.3217 deg (J2000) with an uncertainty of 10 arcsec in radius (90% C.L. statistical and systematic). The updated position is consistent with the counterpart reported before (Schneider et al. GCN 42544, Eyles-Ferris et al. GCN 42546, Liang et al. GCN 42548, Adami et al. GCN 42575). The average FXT 0.5-10 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 9.1 x 10^20 cm^-2 and a photon index of 1.93+/-0.36. The derived average unabsorbed 0.5-10 keV flux is (4.8+/-1.3) x 10^(-13) erg/s/cm^2. 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/42576. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40633] EP251102a: OHP/T193 optical observations
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42575 SUBJECT: EP251102a: OHP/T193 optical observations DATE: 25/11/04 11:32:43 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> C. Adami (LAM/Pytheas/AMU), N.A. Rakotondrainibe (LAM), B. Schneider (LAM), S. Basa (UAR Pytheas), E. Le Floc'h (CEA/Irfu) report on behalf of the MISTRAL GRB collaboration: We carried out observations of the EP251102a (Schneider et al., GCN 42544; Eyles-Ferris et al., GCN 42546; Liang et al., GCN 42548; Mo et al., GCN 42563) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 75 min (15 exposures of 5 min) in the r-band at a midtime of 2025-11-04 03:34:45 UT corresponding to T-T0 = 30.2064 hours. The afterglow is detected in r’ after image subtraction performed relative to r-band images from PanSTARRS. We measured the following preliminary magnitude: r’ = 20.94 +/- 0.07 The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the STDWeb/STDPipe tools (Karpov 2025), is in the AB system, and is not corrected for Galactic extinction. We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Yoann Degot-Longhi. View this GCN Circular online at https://gcn.nasa.gov/circulars/42575. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40632] GRB 251103A: OHP/T193 optical observations
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42574 SUBJECT: GRB 251103A: OHP/T193 optical observations DATE: 25/11/04 11:29:23 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> C. Adami (LAM/Pytheas/AMU), N.A. Rakotondrainibe (LAM), B. Schneider (LAM), S. Basa (UAR Pytheas), E. Le Floc'h (CEA/Irfu) report on behalf of the MISTRAL GRB collaboration: We carried out observations of the GRB 251103A (Hu et al., GCN 42534, Schneider et al., GCN 42535; Fermi GBM Team, GCN 42536; Turpin et al., GCN 42538; Gritsevich et al., GCN 42539, Izzo et al., GCN 42540; Osborne et al., GCN 42551; O'Neill et al., GCN 42543; Ghosh et al., GCN 42545; Schneider et al., GCN 42549; Osborne et al., GCN 42551; Wang et al., GCN 42552; Sonawane et al., GCN 42553; Breeveld et al., GCN 42554; Hellot et al., GCN 42559; Mo et al., GCN 42562; Lipunov et al., GCN 42565; Delaunay et al., GCN 42568; Zheng et al., GCN 42571, Ren et al., GCN 42572) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 94 min (1 exposure of 4 min and 18 exposures of 5 min) in the r-band at a midtime of 2025-11-04 05:24:03 UT corresponding to T-T0 = 24.63 hours. The afterglow is detected in r’ and we measured the following preliminary magnitude: r’ = 22.33 +/- 0.16 The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the STDWeb/STDPipe tools (Karpov 2025), is in the AB system, and is not corrected for Galactic extinction. We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Yoann Degot-Longhi. View this GCN Circular online at https://gcn.nasa.gov/circulars/42574. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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