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

[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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[vsnet-grb-info 40631] GRB 251103A: Xinglong 2.16m optical detection
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42573 SUBJECT: GRB 251103A: Xinglong 2.16m optical detection DATE: 25/11/04 11:27:31 GMT FROM: Youdong HU at GXU <huyoudong072(a)hotmail.com> L. P. Xin (NAOC), Y.-D. Hu, X. Tian (GXU), Y. Zhang, J. Wang, J.-Y. Wei (NAOC) report on behalf of SVOM follow-up team: We observed the field of GRB 251103A (Hu et al., GCN 42534; Fermi GBM Team, GCN 42536; Wang et al., GCN 42552; Sonawane et al., GCN 42553; DeLaunay et al., GCN 42568; Ren et al., GCN 42572). using the 2.16-m telescope located at Xinglong observatory, China, equipped with the BFOSC camera. We obtained 9*200s frames in R-band, starting at 21:11:22 UT on 2025-11-03, about 16.7 hrs after the trigger. The optical afterglow (Schneider et al., GCN 42535; Turpin et al., GCN 42538; Gritsevich et al., GCN 42539; Izzo et al., GCN 42540; O'Neill et al., GCN 42543; Ghosh et al., GCN 42545; Schneider et al., GCN 42549; Breeveld et al., GCN 42554; Hellot et al., GCN 42559; Mo et al., GCN 42562; Zheng et al., GCN 42571) was clearly detected in the stacked image with a magnitude of R=20.78+-0.08 mag at the mid time, which calibrate with nearby SDSS stars. We thank the staff at Xinglong observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/42573. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40629] GRB 251103A: Insight-HXMT detection
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42572 SUBJECT: GRB 251103A: Insight-HXMT detection DATE: 25/11/04 10:49:35 GMT FROM: renyz16607(a)163.com GRB 251103A: Insight-HXMT detection Yang-Zhao Ren, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team: At 2025-11-03T04:46:28.000 (T0), Insight-HXMT/HE detected the burst GRB 251103A, which is also detected by SVOM/ECLAIRs (Hu et al., GCN#42534), Fermi/GBM (Fermi GBM team, GCN #42536), SVOM/GRM (Wang et al., GCN#42552). The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 5.5 +2.5/-2.0 s. The 1s peak rate, measured from T0+0.25 s, is 2447 cnts/sec. The total counts from this burst is 5414 counts. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251103A.png All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org View this GCN Circular online at https://gcn.nasa.gov/circulars/42572. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40617] GRB 251103A: KAIT optical observations
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42571 SUBJECT: GRB 251103A: KAIT optical observations DATE: 25/11/04 08:07:10 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, observed the field of GRB 251103A (Hu et al., GCN 42534; Fermi GBM Team, GCN 42536; Wang et al., GCN 42552; Sonawane et al., GCN 42553; DeLaunay et al., GCN 42568) starting at 11:54 UT, 7.13 hours after the burst. A set of clear (roughly R) filter images were obtained. We clearly detected the afterglow (Schneider et al., GCN 42535; Turpin et al., GCN 42538; Gritsevich et al., GCN 42539; Izzo et al., GCN 42540; O'Neill et al., GCN 42543; Ghosh et al., GCN 42545; Schneider et al., GCN 42549; Breeveld et al., GCN 42554; Hellot et al., GCN 42559; Mo et al., GCN 42562) in our coadd image. We measure its brightness to be 19.4 +/- 0.2 mag (Vega) at mid time of 7.72 hours after the burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/42571. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40621] GRB 251103B: Nanshan/HMT optical upper limit
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42570 SUBJECT: GRB 251103B: Nanshan/HMT optical upper limit DATE: 25/11/04 06:19:28 GMT FROM: sqjiang at NAOC <sqjiang(a)bao.ac.cn> S.Q. Jiang (NAOC), S.Y. Fu (HUST), J. An, X. Liu, L.B. He, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the field of GRB 251103B detected by Swift/BAT (Lanava et al., GCN 42556) and Fermi/GBM (Fermi GBM team, GCN 42555) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 22:31:33 UT on 2025-11-03, i.e., 5.749 hrs after the Swift/BAT trigger, we obtained 25x120 s unfiltered frames. No new optical source is detected in our stacked image within the enhanced XRT error circle (Evans et al., GCN 42558), down to the following 3-sigma limiting magnitude R>20.4 at 6.276 hrs post-burst, calibrated with the nearby PanSTARRS field and the magnitude is not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42570. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40618] GRB 251013A: 7DT detection and Medium-band SED of Afterglow
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42569 SUBJECT: GRB 251013A: 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 40630] GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42568 SUBJECT: GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst DATE: 25/11/04 03:36:10 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Aaron Tohuvavohu (Cosmic Frontier), Samuele Ronchini (GSSI), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report: Swift/BAT did not localize GRB 251103A onboard (T0: 2025-11-03T04:46:28.11 UTC, Fermi Trig 783837993, SVOM Trig sb25110301). The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst in a 2.048 s analysis time bin starting at T0 - 0.0 s with a sqrt(TS) of 61.6. An arcminute localization is found with DeltaLLHOut of 24 and a DeltaLLHPeak of 10.2. See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. The BAT position is RA, Dec = 146.821, 16.104 deg which is RA(J2000) = 09h 47m 17.04s Dec(J2000) = 16d 06’ 14.4″ with an estimated uncertainty of 5 arcmin radius. More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=783838024 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/42568. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40615] GRB 251103B: MITSuME Akeno optical upper limits
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42567 SUBJECT: GRB 251103B: MITSuME Akeno optical upper limits DATE: 25/11/04 03:30:48 GMT FROM: Ichiro Takahashi at Science Tokyo <itakahashi(a)hp.phys.titech.ac.jp> I. Takahashi, H. Hagio, A. Ochi, Y. Kubo, M. Sasada, R. Kato, H. Seki, S. Joshima, Y. Yatsu and N. Kawai (Science Tokyo) report on behalf of the MITSuME collaboration: We observed the field of GRB 251103B detected by Fermi (Fermi GBM team, GCN 42555) and Swift (Lanava et al., GCN 42556) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno. The observation started at 2025-11-03 16:47:11 UT (35 seconds after the trigger). We stacked the images taken under good conditions. We did not detect any obvious point sources within the enhanced Swift/XRT error region (Evans et al., GCN 42558). We obtained the 5-sigma limits of the stacked images as follows: T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits ------------------------------------------------------------------------------------------------ 124 | 2025-11-03 16:48:40 | 80 | Rc>16.6, Ic>16.3 821 | 2025-11-03 17:00:17 | 1020 | g'>17.8, Rc>18.4, Ic>18.1 7041 | 2025-11-03 18:43:57 | 9180 | g'>19.4, Rc>19.5, Ic>19.1 ------------------------------------------------------------------------------------------------ T0+ : Elapsed time after the trigger T-EXP: Total exposure time We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ; https://github.com/MNiwano/Eclaire) View this GCN Circular online at https://gcn.nasa.gov/circulars/42567. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40623] GRB 251103B: MITSuME Akeno optical upper limits
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42567 SUBJECT: GRB 251103B: MITSuME Akeno optical upper limits DATE: 25/11/04 03:30:48 GMT FROM: Ichiro Takahashi at Science Tokyo <itakahashi(a)hp.phys.titech.ac.jp> I. Takahashi, H. Hagio, A. Ochi, Y. Kubo, M. Sasada, R. Kato, H. Seki, S. Joshima, Y. Yatsu and N. Kawai (Science Tokyo) report on behalf of the MITSuME collaboration: We observed the field of GRB 251103B detected by Fermi (Fermi GBM team, GCN 42555) and Swift (Lanava et al., GCN 42556) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno. The observation started at 2025-11-03 16:47:11 UT (35 seconds after the trigger). We stacked the images taken under good conditions. We did not detect any obvious point sources within the enhanced Swift/XRT error region (Evans et al., GCN 42558). We obtained the 5-sigma limits of the stacked images as follows: T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits ------------------------------------------------------------------------------------------------ 124 | 2025-11-03 16:48:40 | 80 | Rc>16.6, Ic>16.3 821 | 2025-11-03 17:00:17 | 1020 | g'>17.8, Rc>18.4, Ic>18.1 7041 | 2025-11-03 18:43:57 | 9180 | g'>19.4, Rc>19.5, Ic>19.1 ------------------------------------------------------------------------------------------------ T0+ : Elapsed time after the trigger T-EXP: Total exposure time We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ; https://github.com/MNiwano/Eclaire) View this GCN Circular online at https://gcn.nasa.gov/circulars/42567. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40619] GRB 251103B: Swift-XRT refined Analysis
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42566 SUBJECT: GRB 251103B: Swift-XRT refined Analysis DATE: 25/11/04 02:13:00 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.8 ks of XRT data for GRB 251103B, from 62 s to 23.6 ks after the trigger. The data comprise 143 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The late-time light curve (from T0+10.3 ks) can be modelled with a power-law decay with a decay index of alpha=1.0 (+/-0.4). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.21 (+/-0.08). The best-fitting absorption column is 9.0 (+/-0.7) x 10^21 cm^-2, in excess of the Galactic value of 3.3 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.09 (+0.22, -0.21) and a best-fitting absorption column of 4.9 (+1.2, -1.1) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (6.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.9 (+1.2, -1.1) x 10^21 cm^-2 Galactic foreground: 3.3 x 10^21 cm^-2 Excess significance: 2.5 sigma Photon index: 2.09 (+0.22, -0.21) If the light curve continues to decay with a power-law decay index of 1.0, the count rate at T+24 hours will be 0.014 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.4 x 10^-13 (9.2 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01409824. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42566. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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