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

[vsnet-grb-info 40184] GRB 251005C: GOTO optical upper limits
by GCN Circulars 05 Oct '25

05 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42115 SUBJECT: GRB 251005C: GOTO optical upper limits DATE: 25/10/05 18:48:41 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz, D. O’Neill, G. Ramsay, P. O’Brien, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, A. Kumar, B. Godson, D. Steeghs, D. K. Galloway, V. Dhillon, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, and J. Casares report on behalf of the GOTO collaboration: We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to GRB 251005C (Page et al., GCN 42113). A targeted observation was performed at 17:48:32 (1.7 hours after trigger), consisting of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations of the same pointings. We find no new optical sources consistent with the Swift/XRT localisation (Goad et al., GCN 42116) to a 3-sigma limiting AB magnitude of L > 19.65 mag. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/42115. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40183] GRB 251005C: Swift detection of a burst
by GCN Circulars 05 Oct '25

05 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42113 SUBJECT: GRB 251005C: Swift detection of a burst DATE: 25/10/05 16:23:27 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> K. L. Page (U Leicester), S. Dichiara (PSU), R. Gupta (NASA GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL) and M. J. Moss (GSFC) report on behalf of the Neil Gehrels Swift Observatory Team: At 16:06:53 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 251005C (trigger=1401726). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 75.673, +16.882 which is RA(J2000) = 05h 02m 42s Dec(J2000) = +16d 52' 54" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 2 sec. The peak count rate was ~4,500 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 16:08:52.2 UT, 118.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 75.68331, 16.88007 which is equivalent to: RA(J2000) = 05h 02m 44.00s Dec(J2000) = +16d 52' 48.3" with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 36 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (3.19 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 5 (+3.76/-3.16) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 122 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.461. Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42113. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40182] GRB 251005C: Enhanced Swift-XRT position
by GCN Circulars 05 Oct '25

05 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42116 SUBJECT: GRB 251005C: Enhanced Swift-XRT position DATE: 25/10/05 19:33:09 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 1541 s of XRT Photon Counting mode data and 2 UVOT images for GRB 251005C, 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 = 75.68325, +16.88054 which is equivalent to: RA (J2000): 05h 02m 43.98s Dec (J2000): +16d 52' 49.9" with an uncertainty of 2.3 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://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/42116. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40180] Fermi trigger No 781367244: Global MASTER-Net observations report
by GCN Circulars 05 Oct '25

05 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42114 SUBJECT: Fermi trigger No 781367244: Global MASTER-Net observations report DATE: 25/10/05 18:15:34 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB251005.60 (trigger No 781367244,19h 54m 28.80s , -08d 55m 12.0s, R=6.5) errorbox 11063 sec after notice time and 11097 sec after trigger time at 2025-10-05 17:32:16 UT, with upper limit up to 17.8 mag. Observations started at twilight. The observations began at zenith distance = 23 deg. The sun altitude is -11.1 deg. The galactic latitude b = -19 deg., longitude l = 32 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3007732 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 11127 | 2025-10-05 17:32:16 | MASTER-SAAO | (19h 53m 05.61s , -08d 35m 40.3s) | C | 60 | 17.2 | 11127 | 2025-10-05 17:32:16 | MASTER-SAAO | (19h 51m 12.16s , -08d 20m 30.0s) | C | 60 | 17.6 | 11226 | 2025-10-05 17:33:55 | MASTER-SAAO | (20h 01m 01.07s , -08d 37m 00.8s) | C | 60 | 17.4 | 11226 | 2025-10-05 17:33:55 | MASTER-SAAO | (19h 59m 07.53s , -08d 21m 50.9s) | C | 60 | 17.8 | 11424 | 2025-10-05 17:37:13 | MASTER-SAAO | (19h 44m 10.05s , -10d 29m 55.4s) | C | 60 | 17.5 | 11424 | 2025-10-05 17:37:13 | MASTER-SAAO | (19h 42m 15.83s , -10d 14m 44.1s) | C | 60 | 17.8 | 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/42114. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40181] GRB 251002A: Mondy/AZT-33IK optical observations
by GCN Circulars 05 Oct '25

05 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42110 SUBJECT: GRB 251002A: Mondy/AZT-33IK optical observations DATE: 25/10/05 07:05:17 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 251002A detected by SVOM (Saccardi et. al, GCN 42060) in the R-filter with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy). The observations began on 2025-10-03 17:00 UT, i.e. ~0.88 days since trigger and consisted of 30x120 s exposures. The optical source found by SVOM (Palmerio et. al, GCN 42061) at z = 2.178 (Saccardi et. al, GCN 42076) and also observed by (Turpin et. al, GCN 42062; Jelinek et. al, GCN 42063; Juliá-Maroto et. al, GCN 42064; Moskvitin et. al, GCN 42065; Perez-Garcia et. al, GCN 42066; Saccardi et. al, GCN 42076; Mandarakas et. al, GCN 42077; Cao et. al, GCN 42078; Schneider et. al, GCN 42080; Pankov et. al, GCN 42081; Leonini et. al, GCN 42082; Odeh et. al, GCN 42087; Wortley et. al, GCN 42091; Shilling, GCN 42099; Calapai & Giorgio, GCN 42101) is detected in the co-add image of 30x120 s. Preliminary photometry and observation details are presented below: Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (nxs) (3sigma) 2025-10-03 17:00:32 0.88586 30x120 R 20.96 0.12 22.0 The photometry was calibrated using reference stars from (Moskvitin et. al, GCN 42065) and not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42110. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40179] Swift/BAT trigger 1401726: GOTO optical upper limits
by GCN Circulars 05 Oct '25

05 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42115 SUBJECT: Swift/BAT trigger 1401726: GOTO optical upper limits DATE: 25/10/05 18:48:41 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz, D. O’Neill, G. Ramsay, P. O’Brien, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, A. Kumar, B. Godson, D. Steeghs, D. K. Galloway, V. Dhillon, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, and J. Casares report on behalf of the GOTO collaboration: We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to Swift/BAT trigger 1401726. The current difficulties with the distribution of GCN circulars means we are unsure of the official designation of this burst at the time of submission. A targeted observation was performed at 17:48:32 (1.7 hours after trigger), consisting of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations of the same pointings. We find no new optical sources consistent with the Swift/XRT localisation to a 3-sigma limiting AB magnitude of L > 19.65 mag. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/42115. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40177] GRB 251002A: Insight-HXMT detection
by GCN Circulars 05 Oct '25

05 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42109 SUBJECT: GRB 251002A: Insight-HXMT detection DATE: 25/10/05 06:33:10 GMT FROM: xueyuan zao <zaoxueyuan(a)gmail.com> Xue-Yuan Zao, Zheng-Hang Yu, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team: At 2025-10-02T20:14:52.800 (T0), Insight-HXMT/HE detected a long burst GRB 251002A, which is also detected by Fermi/GBM (Jacob Smith et al., GCN #42093) and SVOM/ECLAIRs (A. Saccardi et al., GCN #42060). The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 13.8 +2.3/-3.1 s. The 1s peak rate, measured from T0+6.050 s, is 1080 cnts/sec. The total counts from this burst is 4528 counts. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251002A.png All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 30-1000 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/42109. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40176] GRB 251005A: Fermi GBM Final Real-time Localization
by GCN Circulars 05 Oct '25

05 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42112 SUBJECT: GRB 251005A: Fermi GBM Final Real-time Localization DATE: 25/10/05 14:37:49 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 14:27:19 UT on 5 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251005A (trigger 781367244.128264 / 251005602). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 298.6, Dec = -8.9 (J2000 degrees, equivalent to J2000 19h 54m, -8d 54'), with a statistical uncertainty of 6.5 degrees. The angle from the Fermi LAT boresight is 104.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251005602/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251005602/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251005602/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42112. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40178] GRB 251005A: Fermi GBM Final Localization
by GCN Circulars 05 Oct '25

05 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42111 SUBJECT: GRB 251005A: Fermi GBM Final Localization DATE: 25/10/05 09:53:14 GMT FROM: Utkarsh Pathak at IIT Bombay <utkarshpathak.07(a)gmail.com> The Fermi GBM team reports the detection of a likely LONG GRB "At 05:27:08.25 UT on 05 October 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251005A (trigger 781334833/251005227). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 227.84, Dec = 5.07 (J2000 degrees, equivalent to J2000 15h 11m, 5d 04'), with a statistical uncertainty of 4.90 degrees. The angle from the Fermi LAT boresight is 86 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251005227/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251005227/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251005227/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/42111. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40175] GRB 251002A: Insight-HXMT detection
by GCN Circulars 05 Oct '25

05 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42108 SUBJECT: GRB 251002A: Insight-HXMT detection DATE: 25/10/05 05:30:19 GMT FROM: xueyuan zao <zaoxueyuan(a)gmail.com> Xue-Yuan Zao, Zheng-Hang Yu, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team: At 2025-10-02T20:14:52.800 (T0), Insight-HXMT/HE detected a long burst GRB 251002A, which is also detected by Fermi/GBM (Jacob Smith et al., GCN #42093) and SVOM/ECLAIRs (A. Saccardi et al., GCN #42060). The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 13.8 +2.3/-3.1 s. The 1s peak rate, measured from T0+6.050 s, is 1080 cnts/sec. The total counts from this burst is 4528 counts. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251002A.png All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 30-1000 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/42108. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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