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[vsnet-grb-info 40260] GRB 251009A: GECAM-B detection of a short burst
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42190 SUBJECT: GRB 251009A: GECAM-B detection of a short burst DATE: 25/10/10 16:22:21 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered on-ground by the short burst GRB 251009A at 2025-10-09T15:58:56.300 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN#42179), SVOM/GRM (Wang et al., GCN#42185) and Insight-HXMT (Wang et al., GCN#42189). According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of a single pulse with a duration (T90) of 0.14 +0.08/-0.08 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251009A.png Using the automatic on-ground localization pipeline, GECAM-B localized this burst to the following position (J2000): Ra: 103.2 deg Dec: 34.2 deg Err: 21.4 deg (1-sigma, statistical only) Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/42190. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40259] GRB 251009A: Insight-HXMT detection of a short burst
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42189 SUBJECT: GRB 251009A: Insight-HXMT detection of a short burst DATE: 25/10/10 16:17:00 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team: At 2025-10-09T15:58:56.350 (T0), Insight-HXMT/HE detected the burst GRB 251009A, which is also detected by Fermi/GBM (Fermi GBM team, GCN#42179) and SVOM/GRM (Wang et al., GCN#42185). The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 0.65 +0.31/-0.28 s. The total counts from this burst is 998 counts. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251009A.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/42189. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40258] GRB 251009B (short): Glowbug gamma-ray detection
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42188 SUBJECT: GRB 251009B (short): Glowbug gamma-ray detection DATE: 25/10/10 16:14:04 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251009B, which was also detected by Insight-HXMT (GCN 41287). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-10-09 01:51:14.176 with a duration of 1.0 s and a total significance of about 13.1 sigma. The light curve comprises two peaks at ~T0+0.2s and ~T0+0.9s. The best-fit localization is RA, Decl. (J2000, deg) = 155.1, 24.1 with a radius of 25.3 deg (95% confidence), with a highly uncertain systematic uncertainty. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS, and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42188. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40257] GRB 251009B: Insight-HXMT detection of a short burst
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42187 SUBJECT: GRB 251009B: Insight-HXMT detection of a short burst DATE: 25/10/10 15:50:38 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team: At 2025-10-09T01:51:15.250 (T0), Insight-HXMT/HE detected the burst GRB 251009B, which is also detected by SVOM/GRM. The Insight-HXMT/HE light curve mainly consists of double pulses with a T90 of 1.00 +0.15/-0.05 s. The total counts from this burst is 2442 counts. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251009B.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/42187. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40256] GRB 251007A: Swift-BAT refined analysis
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42186 SUBJECT: GRB 251007A: Swift-BAT refined analysis DATE: 25/10/10 14:08:25 GMT FROM: Takanori Sakamoto at AGU <tsakamoto(a)phys.aoyama.ac.jp> S. Laha (GSFC/UMBC), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+303 sec from the recent telemetry downlink, we report further analysis of BAT GRB 251007A (trigger #1402466) (Ambrosi, et al., GCN Circ. 42146). The BAT ground-calculated position is RA, Dec = 128.162, 21.810 deg which is RA(J2000) = 08h 32m 38.8s Dec(J2000) = +21d 48' 36.6" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 85%. The mask-weighted light curve shows a complex structure starting at ~T-1 sec, peaking at T+56 sec, and decaying to background at T+110 sec. T90 (15-350 keV) is 64.19 +- 5.17 sec (estimated error including systematics). The time-averaged spectrum from T-0.04 to T+103.43 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.32 +- 0.03. The fluence in the 15-150 keV band is 1.04 +- 0.02 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+56.14 sec in the 15-150 keV band is 9.5 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1402466 View this GCN Circular online at https://gcn.nasa.gov/circulars/42186. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40255] GRB 251009A: SVOM/GRM observation of short GRB with possible tail emission
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42185 SUBJECT: GRB 251009A: SVOM/GRM observation of short GRB with possible tail emission DATE: 25/10/10 13:32:03 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shu-Xu Yi, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Frédéric Piron (LUPM) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a short burst GRB 251009A (SVOM trigger reference: sb25100902) at 2025-10-09T15:58:56.500 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN#42179). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a narrow spike followed by a weak tail emission with a T90 of 0.32 +0.05/-0.11 s in the 15-5000 keV band, which is somewhat similar to extragalactic magnetar giant flare. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251009A.png 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. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42185. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40254] GRB 251007A: SVOM/GRM observation
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42184 SUBJECT: GRB 251007A: SVOM/GRM observation DATE: 25/10/10 12:47:58 GMT FROM: yzh807926(a)163.com SVOM/GRM team: Zheng-Hang Yu, Chen-Wei Wang, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Feliu Lacreu (IAP), Sebastien Guillot (IRAP), Olivier GODET (IRAP), Marius Brunet (IRAP), Frédéric Piron (LUPM), Jean-Luc Atteia (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a burst GRB 251007A (SVOM trigger reference: sb25100703) at 2025-10-07T19:37:53.000 UTC (T0), which is also detected by Swift/BAT (Ambrosi et al. 2025, GCN #42146), Glowbug (Cheung et al. 2025, GCN #42151) and CALET/GBM (A. Yoshida et al. 2025, GCN #42156). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a precursor followed by a main episode with multiple peaks a T90 of 58.0 +1.5/-5.5 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251007A.png In addition, the position of this burst, as determined by Swift/BAT (RA= 128.1775, DEC= 21.8138, GCN#42146), is located at about 49 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. Nevertheless, ECLAIRs detected the burst above 50 keV through its shield. With this localization, the time-averaged spectrum from T0-50 to T0+30 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.27 +0.04/-0.04 and the cutoff energy, parameterized as Epeak, is 761 +219/-152 keV. The event fluence (10-1000 keV) in this time interval is (3.97 +0.14/-0.15)E-05 erg/cm^2. The localization of GRB 251007A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251007A_amati.png 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. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Zheng-Hang Yu(IHEP)(zhyu(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42184. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40253] GRB 251007A: Insight-HXMT detection
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42183 SUBJECT: GRB 251007A: Insight-HXMT detection DATE: 25/10/10 12:33:04 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> Chen-Wei Wang, Zheng-Hang Yu, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team: At 2025-10-07T19:37:51.750 (T0), Insight-HXMT/HE detected the burst GRB 251007A, which is also detected by Swift/BAT (E. Ambrosi et al, GCN#42146), Glowbug (C.C. Cheun et al., GCN#42151), CALET/GBM (A. Yoshida et al., GCN#42156) and AstroSat (S. Salunke et al., GCN#42167). The Insight-HXMT/HE light curve mainly consists of multi-pulses with a T90 of 57.4 +1.8/-16.2 s. The 1s peak rate, measured from T0+0.7 s, is 7246 cnts/sec. The total counts from this burst is 52938 counts. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251007A.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/42183. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40252] GRB 251006A: CALET Gamma-Ray Burst Monitor detection
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42182 SUBJECT: GRB 251006A: CALET Gamma-Ray Burst Monitor detection DATE: 25/10/10 10:17:47 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> T. Sakamoto, A. Yoshida, S. Sugita, Y. Kawakubo (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration: The short GRB 251006A (Fermi GBM Final Real-time Localization: Fermi GBM team, GCN Circ. 42124; Glowbug gamma-ray detection: Cheung et al., GCN Circ. 42130; Swift/BAT-GUANO subthreshold detection: DeLaunay et al., GCN Circ. 42144; Fermi GBM Observation: Palafox et al., GCN Circ. 42175) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 13:27:35.21 UTC on 6 October 2025 (https://cgbm.calet.jp/cgbm_trigger/flight/1443792004/index.html) The burst signal was seen by only the SGM detector. No real-time CGBM GCN notice was distributed about this trigger because the real-time communication from the ISS was off (loss of signal). The burst light curve shows a single pulse that starts at T-0.22 sec and ends at T+0.04 sec. The T90 and T50 durations measured by the SGM data are 0.21 +/- 0.05 sec and 0.11 +/- 0.05 sec (40-1000 keV), respectively. The ground-processed light curve is available at https://cgbm.calet.jp/cgbm_trigger/ground/1443792004/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at Waseda University. View this GCN Circular online at https://gcn.nasa.gov/circulars/42182. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40251] GRB 251007B - SVOM/ECLAIRs refined analysis
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42181 SUBJECT: GRB 251007B - SVOM/ECLAIRs refined analysis DATE: 25/10/10 08:31:06 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Authors: O. Godet, S. Guillot (IRAP), F. Lacreu (IAP), M. Brunet, N. A. Webb (IRAP) Using the event-by-event data downloaded through the X-band ground stations, we report further analysis of ECLAIRs observations of GRB 251007B (SVOM burst-id sb25100703). The burst that triggered ECLAIRs onboard (Webb et al., GCN Circ. #42148) consists of a simple peak structure with a duration of T90 = 33.16 -6.76 / +3.58 s in the 4-120 keV energy band. The time-averaged spectrum from T0-18 s to T0+22 s (T0 = 2025-10-07T19:43:23) in the energy range 5-70 keV is best fitted by a powerlaw model with a photon index of 1.58 +0.15/-0.14. With this model, the total 4-120 keV fluence is (9.0 +0.4/-0.2)e-7 erg/cm^2. All the quoted errors are at the 68% confidence level. 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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: O. Godet (IRAP) (ogodet at irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/42181. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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