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[vsnet-grb-info 40647] GRB 251103B: Swift/UVOT Upper Limits
by GCN Circulars 05 Nov '25

05 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42588 SUBJECT: GRB 251103B: Swift/UVOT Upper Limits DATE: 25/11/05 13:58:01 GMT FROM: Alice Breeveld at MSSL-UCL <a.breeveld(a)ucl.ac.uk> A.A. Breeveld (UCL-MSSL) and S. Lanava (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251103B 140 s after the BAT trigger (Lanava et al., GCN Circ. 42556). No optical afterglow consistent with the enhanced XRT position (Evans et al., GCN Circ. 42558)is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u_FC 140 390 246 >20.2 white 420 1363 245 >21.1 v 470 1413 117 >19.0 b 395 1339 97 >19.8 w1 519 1462 97 >18.8 m2 494 1437 117 >18.8 w2 445 1389 117 >19.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.256 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42588. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40646] LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
by GCN Circulars 05 Nov '25

05 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42587 SUBJECT: LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate DATE: 25/11/05 13:43:35 GMT FROM: Jeremias Sobrinho <jeremiasbezerra.sobrinho(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251105aj during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-11-05 12:59:19.959 UTC (GPS time: 1446382777.959). The candidate was found by the Aframe [1], cWB [2], cWB BBH [3], GstLAL [4], MBTA [5], PyCBC Live [6], and SPIIR [7] analysis pipelines. S251105aj is an event of interest because its false alarm rate, as estimated by the online analysis, is 8e-13 Hz, or about one in 1e5 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251105aj The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), or NSBH (<1%). Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [8] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [8] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The source chirp mass falls with highest probability in the bin (22.0, 44.0) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [9], distributed via GCN and SCiMMA notices about 27 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [9], distributed via GCN and SCiMMA notices about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 721 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2071 +/- 545 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Marx et al. PRD 111, 042010 (2025) doi:10.1103/PhysRevD.111.042010 [2] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004 [3] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [4] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [5] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [6] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [7] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [8] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [9] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42587. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40645] GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
by GCN Circulars 05 Nov '25

05 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42586 SUBJECT: GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission DATE: 25/11/05 13:22:13 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Marius Brunet (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a burst GRB 251105B (SVOM trigger reference: sb25110501) at 2025-11-05T00:58:34.700 UTC (T0). 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 hard spike followed by a FRED shape long pulse with a T90 of 43.6 +6.0/-5.4 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251105B.png ECLAIRs was collecting data at the time of this burst but no signal was detected, suggesting the burst localized outside ECLAIRs FoV. 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/42586. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40644] Fermi GRB 251105A: Global MASTER-Net observations report
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42585 SUBJECT: Fermi GRB 251105A: Global MASTER-Net observations report DATE: 25/11/05 05:16:15 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 251105A ( Fermi GBM team, GCN 42584) errorbox 129 sec after notice time and 150 sec after trigger time at 2025-11-05 04:43:37 UT, with upper limit up to 18.3 mag. The observations began at zenith distance = 43 deg. The sun altitude is -43.0 deg. The galactic latitude b = -25 deg., longitude l = 190 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3033298 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 166 | 2025-11-05 04:43:37 | MASTER-OAFA | (04h 39m 45.81s , +05d 19m 45.6s) | C | 30 | 17.7 | 207 | 2025-11-05 04:44:13 | MASTER-OAFA | (04h 39m 45.84s , +05d 19m 46.9s) | C | 40 | 17.9 | 258 | 2025-11-05 04:44:59 | MASTER-OAFA | (04h 39m 45.88s , +05d 19m 48.6s) | C | 50 | 18.1 | 319 | 2025-11-05 04:45:55 | MASTER-OAFA | (04h 39m 45.91s , +05d 19m 50.3s) | C | 60 | 18.0 | 390 | 2025-11-05 04:47:01 | MASTER-OAFA | (04h 39m 45.96s , +05d 19m 52.4s) | C | 70 | 18.1 | 957 | 2025-11-05 04:56:33 | MASTER-OAFA | (04h 38m 41.39s , +07d 10m 46.5s) | C | 60 | 18.2 | 1023 | 2025-11-05 04:57:38 | MASTER-OAFA | (04h 38m 41.37s , +07d 10m 48.1s) | C | 60 | 18.3 | 1088 | 2025-11-05 04:58:44 | MASTER-OAFA | (04h 38m 41.40s , +07d 10m 49.8s) | C | 60 | 18.3 | 1154 | 2025-11-05 04:59:50 | MASTER-OAFA | (04h 38m 41.39s , +07d 10m 51.5s) | C | 60 | 18.3 | 1219 | 2025-11-05 05:00:55 | MASTER-OAFA | (04h 38m 41.39s , +07d 10m 53.2s) | C | 60 | 18.3 | 1285 | 2025-11-05 05:02:01 | MASTER-OAFA | (04h 38m 41.39s , +07d 10m 54.7s) | C | 60 | 18.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42585. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40643] GRB 251105A: Fermi GBM Final Real-time Localization
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42584 SUBJECT: GRB 251105A: Fermi GBM Final Real-time Localization DATE: 25/11/05 04:51:43 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 04:41:06 UT on 5 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251105A (trigger 784010471.401264 / 251105195). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 69.6, Dec = 7.1 (J2000 degrees, equivalent to J2000 04h 38m, 7d 05'), with a statistical uncertainty of 3.3 degrees. The angle from the Fermi LAT boresight is 41.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251105195/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251105195/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251105195/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42584. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40642] Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
by GCN Circulars 04 Nov '25

04 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42583 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB DATE: 25/11/05 01:16:51 GMT FROM: oindabimukherjee(a)gmail.com O. Mukherjee (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 783986701/251104920 at 22:04:56.89 UT on 04 November 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to solar flare." View this GCN Circular online at https://gcn.nasa.gov/circulars/42583. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[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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