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

[vsnet-grb-info 40280] GRB 251011A: Insight-HXMT detection
by GCN Circulars 12 Oct '25

12 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42210 SUBJECT: GRB 251011A: Insight-HXMT detection DATE: 25/10/12 16:37:23 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> Chen-Wei Wang, Xing-Hao Luo, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team: At 2025-10-11T03:41:40.000 (T0), Insight-HXMT/HE detected the burst GRB 251011A, which is also detected by Fermi/GBM (Fermi GBM team, GCN#42195) and AstroSat (M. Tembhurnikar et al., GCN#42199). The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 3.6 +1.6/-1.4 s. The 1s peak rate, measured from T0, is 788 cnts/sec. The total counts from this burst is 1444 counts. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251011A.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/42210. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40279] GRB 251011B: Swift/UVOT Upper Limits
by GCN Circulars 12 Oct '25

12 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42209 SUBJECT: GRB 251011B: Swift/UVOT Upper Limits DATE: 25/10/12 15:56:51 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) and A. D'Ai (INAF-IASFPA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251011B 107 s after the BAT trigger (D'Ai et al., GCN Circ. 42197). No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 42201) 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 white_FC 107 257 147 >20.9 white 107 257 147 >20.9 u 320 463 141 >20.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.017 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42209. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40278] Fermi GRB 251011A: Global MASTER-Net observations report
by GCN Circulars 12 Oct '25

12 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42208 SUBJECT: Fermi GRB 251011A: Global MASTER-Net observations report DATE: 25/10/12 15:31:51 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-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 251011A ( Fermi GBM team, GCN 42195) errorbox 1 days 37513 sec after notice time and 1 days 37548 sec after trigger time at 2025-10-12 14:07:28 UT, with upper limit up to 19.0 mag. The observations began at zenith distance = 21 deg. The sun altitude is -34.7 deg. The galactic latitude b = -19 deg., longitude l = 116 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3012037 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 123979 | 2025-10-12 14:07:28 | MASTER-Tunka | (00h 19m 58.96s , +42d 27m 50.2s) | C | 60 | 19.0 | 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/42208. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40277] GRB 251012A: Fermi GBM Final Real-time Localization
by GCN Circulars 12 Oct '25

12 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42207 SUBJECT: GRB 251012A: Fermi GBM Final Real-time Localization DATE: 25/10/12 14:56:50 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 SHORT GRB At 14:46:27 UT on 12 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251012A (trigger 781973192.204998 / 251012616). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 291.6, Dec = 7.5 (J2000 degrees, equivalent to J2000 19h 26m, 7d 30'), with a statistical uncertainty of 9.9 degrees. The angle from the Fermi LAT boresight is 59.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251012616/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251012616/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251012616/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42207. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40276] GRB 251011B: SVOM/GRM observation
by GCN Circulars 12 Oct '25

12 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42206 SUBJECT: GRB 251011B: SVOM/GRM observation DATE: 25/10/12 08:26:34 GMT FROM: xueyuan zao <zaoxueyuan(a)gmail.com> SVOM/GRM team: Xue-Yuan Zao, Zheng-Hang Yu, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Sebastien Guillot (IRAP), Stéphane Schanne (CEA), Nicolas Dagoneau Report on behalf of the SVOM team: SVOM/GRM detected the burst GRB 251011B at 2025-10-11T07:08:22.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42196) and Swift/BAT (A. D'Ai et al., GCN #42197). With the event-by-event data downloaded through the X-band ground station, we conducted the standard analysis pipeline of GRB 251011B. The GRM light curve shows that this burst consists of a single pulse with a T90 of 48 +9/-10 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251011B.png In addition, the position of this burst, as determined by Fermi/GBM (RA= 5.3, DEC= -56.1, GCN#42196), is located at about 85.17 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-15 to T0+30 s is best fitted by a power law function. The power law index is 2.22 +0.23/-0.19. The event fluence (10-1000 keV) in this time interval is (3.56 +0.56/-0.82)E-06 erg/cm^2. 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/GRM point of contact for this burst is: Xue-Yuan Zao (IHEP) (zaoxy(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42206. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40275] GRB 251011B: Swift-XRT refined Analysis
by GCN Circulars 12 Oct '25

12 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42205 SUBJECT: GRB 251011B: Swift-XRT refined Analysis DATE: 25/10/12 07:29:18 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M. Ferro (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 5.1 ks of XRT data for GRB 251011B, from 85 s to 61.7 ks after the trigger. The data comprise 112 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 light curve can be modelled with an initial power-law decay with an index of alpha=3.12 (+/-0.08), followed by a break at T+579 s to an alpha of 0.57 (+0.07, -0.20). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.15 (+/-0.12). The best-fitting absorption column is 1.8 (+0.4, -0.3) x 10^21 cm^-2, in excess of the Galactic value of 1.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.1 x 10^-11 (4.5 x 10^-11) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 1.8 (+0.4, -0.3) x 10^21 cm^-2 Galactic foreground: 1.7 x 10^20 cm^-2 Excess significance: 8.4 sigma Photon index: 2.15 (+/-0.12) If the light curve continues to decay with a power-law decay index of 0.57, the count rate at T+24 hours will be 0.013 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.0 x 10^-13 (5.7 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/01403191. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42205. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40274] GRB 251011B: Fermi GBM Observation
by GCN Circulars 11 Oct '25

11 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42204 SUBJECT: GRB 251011B: Fermi GBM Observation DATE: 25/10/12 00:26:55 GMT FROM: oindabimukherjee(a)gmail.com O. Mukherjee (USRA), C. Meegan (UAH), U. Pathak (IIT Bombay) and L. Scotton (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 07:08:21.91 UT on 11 October 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251011B (trigger 781859306/251011297). which was also detected by Swift BAT (A. D'Ai et al. 2025, GCN 42197), and Swift XRT (P.A. Evans et al. 2025, GCN 42201). The Fermi GBM on-ground location is consistent with the Swift BAT position. The angle from the Fermi LAT boresight is 81.8 degrees. The GBM light curve consists of a single pulse with a duration (T90) of about 35 s (50-300 keV). The time-averaged spectrum from T0-8.0 to T0+26.5 s is best fit by a Band function with Epeak = 36 +/- 5 keV, alpha = 0.4 +/- 0.7, and beta = -2.2 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (3.3 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.58 s in the 10-1000 keV band is 3 +/- 0.2 ph/s/cm^2. 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/42204. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40273] GRB 251011B : MASTER optical observations
by GCN Circulars 11 Oct '25

11 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42203 SUBJECT: GRB 251011B : MASTER optical observations DATE: 25/10/11 23:11:20 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> P.Balanutsa, V.Lipunov, A.Kuznetsov, G.Antipov, I.Panchenko, K.Zhirkov, N.Tiurina, A.Sankovich, Ya.Kechin, M.Shilova, A.Chasovnikov, V.Topolev, V.Senik, D.Vlasenko, Yu.Tselik, E.Gorbovskoy(Lomonosov MSU), R.Podesta, C.Francile, F. Podesta, E. Gonzalez (OAFA, San Juan Uni.,Argentina); D.Buckley, (SAAO, South Africa) O.Gress, N.Budnev (ISU, Irkutsk), A. Sosnovskiy (CrAO RAS), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), V.M.Pillet, R.Rebolo Lopez (The Instituto de Astrofisica de Canarias, Spain), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez,J.Martinez,A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysic Observatory, Mexico) The MASTER-OAFA robotic telescope of the MASTER Global Robotic Net [1,2,3,4] started GRB 251011B (Fermi GCN 42196, Swift: D'Ai et al. GCN 42197, XRT Evans et al. GCN 42201, Ttrigger=2025-10-11 07:08:22UT XRT RA,Dec(2000)=00h 52m 56.33s,-62d 02' 00.2") at 2025-10-11 07:09:27 with 10s expositions at 48 deg.altitude There is no optical counterpart on a single images Observations and reduction will be continued. Tstart(+exp), UT RADec(2000) of MASTERsquarecent. Exp,s mlim 2025-10-11 07:09:07 00h 53m 53.80s -61d 58m 00.8s 10 18.0 2025-10-11 07:09:23 00h 53m 53.92s -61d 58m 00.0s 10 18.0 2025-10-11 07:09:39 00h 53m 53.86s -61d 58m 00.6s 20 18.6 2025-10-11 07:10:05 00h 53m 53.91s -61d 58m 00.5s 20 18.9 2025-10-11 07:10:31 00h 53m 54.05s -61d 57m 59.3s 30 18.0 2025-10-11 07:11:06 00h 53m 54.18s -61d 57m 59.2s 30 18.0 2025-10-11 07:11:43 00h 53m 54.30s -61d 57m 59.1s 40 18.3 2025-10-11 07:12:29 00h 53m 54.50s -61d 57m 58.5s 50 18.8 2025-10-11 07:13:25 00h 53m 54.74s -61d 57m 58.3s 60 19.2 2025-10-11 07:14:32 00h 53m 55.02s -61d 57m 57.6s 70 19.6 2025-10-11 07:15:47 00h 53m 55.39s -61d 57m 57.1s 90 19.6 2025-10-11 07:17:23 00h 53m 55.79s -61d 57m 56.7s 110 19.6 2025-10-11 07:19:19 00h 53m 56.33s -61d 57m 55.8s 130 19.6 2025-10-11 07:21:35 00h 53m 57.00s -61d 57m 55.1s 160 19.6 up to 2025-10-11 09:17:08. [1] Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L [2] Lipunov et al. 2022, Universe, Vol. 8(5), id.271 [3] Lipunov et a. 2019, ARep, vol.63, 293 [4] Lipunov V., Kornilov V., Gorbovskoy E., Tiurina N., Kuznetsov A. 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http://www.pereplet.ru/lipunov/625.html#625 View this GCN Circular online at https://gcn.nasa.gov/circulars/42203. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40272] GRB 251011C: Fermi GBM Final Real-time Localization
by GCN Circulars 11 Oct '25

11 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42202 SUBJECT: GRB 251011C: Fermi GBM Final Real-time Localization DATE: 25/10/11 22:22:00 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 22:11:20 UT on 11 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251011C (trigger 781913485.841388 / 251011925). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 164.7, Dec = -2.9 (J2000 degrees, equivalent to J2000 10h 58m, -2d 53'), with a statistical uncertainty of 4.6 degrees. The angle from the Fermi LAT boresight is 48.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011925/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011925/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011925/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42202. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40271] GRB 251011B: Enhanced Swift-XRT position
by GCN Circulars 11 Oct '25

11 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42201 SUBJECT: GRB 251011B: Enhanced Swift-XRT position DATE: 25/10/11 14:07:46 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 243 s of XRT Photon Counting mode data and 1 UVOT images for GRB 251011B, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 13.23469, -62.03340 which is equivalent to: RA (J2000): 00h 52m 56.33s Dec (J2000): -62d 02' 00.2" with an uncertainty of 2.4 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at https://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42201. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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