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

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0