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

[vsnet-grb-info 40270] GRB 251010A: AstroSat CZTI detection
by GCN Circulars 11 Oct '25

11 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42200 SUBJECT: GRB 251010A: AstroSat CZTI detection DATE: 25/10/11 12:09:34 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Goyal (IITB), A. Arya (IITB), U. Pathak (IITB), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of GRB 251010A which was also detected by Fermi GBM (GCN Circ. 42192). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed a broad peak of emission with the strongest peak at 2025-10-10 17:44:27.50 UTC. The measured peak count rate associated with the burst is 82 (+38, -8) counts/s above the background in the combined data of all quadrants, with a total of 628 (+155, -170) counts. The local mean background count rate was 292 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 9.5 (+3.1, -2.3) s. The source was also faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42200. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40269] GRB 251011A: AstroSat CZTI detection
by GCN Circulars 11 Oct '25

11 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42199 SUBJECT: GRB 251011A: AstroSat CZTI detection DATE: 25/10/11 09:26:10 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), Harsha K. H. (IUCAA), A. Arya (IITB), A. Goyal (IITB), U. Pathak (IITB), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 251011A which was also detected by Fermi GBM (GCN Circ. 42195). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-10-11 03:41:37.50 UTC. The measured peak count rate associated with the burst is 200 (+32, -29) counts/s above the background in the combined data three quadrants out of four, with a total of 743 (+117, -127) counts. The local mean background count rate was 208 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 6.5 (+2.1, -1.9) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed a peak of emission at 2025-10-11 03:41:37 UTC. The measured peak count rate associated with the burst is 356 (+68, -62) counts/s above the background in the combined data of all quadrants, with a total of 952 (+242, -256) counts. The local mean background count rate was 1335 (+7, -8) counts/s. We measure a T90 of 5.9 (+2.1, -2.9) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42199. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40268] GRB 251009B: SVOM/GRM observation of short GRB
by GCN Circulars 11 Oct '25

11 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42198 SUBJECT: GRB 251009B: SVOM/GRM observation of short GRB DATE: 25/10/11 08:12:07 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: Stéphane Schanne (CEA), Jean-Luc Atteia (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground by a short burst GRB 251009B at 2025-10-09T01:51:15.350 UTC (T0), which is also detected by Insight-HXMT (Wang et al., GCN#42187), Glowbug (C.C. Cheung et al., GCN#42188). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a double spikes with a T90 of 1.2 +0.75/-0.45 s in the 15-5000 keV band, the signal mainly appears above 100 keV. No significant signal is detected by ECLAIRs, suggesting the burst is outside the ECLAIRs FoV. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251009B.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/42198. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40267] GRB 251011B: Swift detection of a burst
by GCN Circulars 11 Oct '25

11 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42197 SUBJECT: GRB 251011B: Swift detection of a burst DATE: 25/10/11 07:29:21 GMT FROM: Antonino D'Ai' at INAF <antonino.dai(a)inaf.it> A. D'Ai (INAF-IASFPA), E. Ambrosi (INAF-IASFPA), V. D'Elia (SSDC & INAF-OAR), R. Gupta (NASA GSFC), N. P. M. Kuin (UCL-MSSL), A. Melandri (INAF-OAR), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 07:08:22.33 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 251011B (trigger=1403191). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 13.287, -62.032 which is RA(J2000) = 00h 53m 09s Dec(J2000) = -62d 01' 55" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 150 seconds. The peak count rate was ~3000 counts/sec (15-350 keV) at ~0 sec after the trigger. The XRT began observing the field at 07:09:58.8 UT, 96.5 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 13.23523, -62.03269 which is equivalent to: RA(J2000) = 00h 52m 56.46s Dec(J2000) = -62d 01' 57.7" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 87 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 (1.68 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.5 (+3.47/-2.92) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 1.95e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT data are unavailable at this time. Burst Advocate for this burst is A. D'Ai (antonino.dai AT inaf.it). 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/42197. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40266] GRB 251011B: Fermi GBM Final Real-time Localization
by GCN Circulars 11 Oct '25

11 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42196 SUBJECT: GRB 251011B: Fermi GBM Final Real-time Localization DATE: 25/10/11 07:19:01 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 07:08:21 UT on 11 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251011B (trigger 781859306.91454 / 251011297). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 5.3, Dec = -56.1 (J2000 degrees, equivalent to J2000 00h 21m, -56d 06'), with a statistical uncertainty of 5.3 degrees. The angle from the Fermi LAT boresight is 78.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011297/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011297/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011297/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42196. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40265] GRB 251011A: Fermi GBM Final Real-time Localization
by GCN Circulars 11 Oct '25

11 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42195 SUBJECT: GRB 251011A: Fermi GBM Final Real-time Localization DATE: 25/10/11 03:52:08 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 03:41:40 UT on 11 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251011A (trigger 781846905.087994 / 251011154). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 2.6, Dec = 43.3 (J2000 degrees, equivalent to J2000 00h 10m, 43d 17'), with a statistical uncertainty of 2.4 degrees. The angle from the Fermi LAT boresight is 63.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011154/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011154/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011154/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42195. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40264] Fermi Gamma-ray Burst Monitor trigger 781824269/251010892 is not a GRB
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42194 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 781824269/251010892 is not a GRB DATE: 25/10/10 23:06:32 GMT FROM: rhamburg(a)usra.edu R. Hamburg (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 781824269/251010892 at 21:24:24.75 UT on 10 October 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/42194. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40263] GRB 251007B: Swift/UVOT Upper Limits
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42193 SUBJECT: GRB 251007B: Swift/UVOT Upper Limits DATE: 25/10/10 18:00:23 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> GRB 251007B: Swift/UVOT Upper Limits M. H. Siegel (PSU) and A. Melandri (INAF-OAR) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251007B 152 s after the BAT trigger (Melandri et al., GCN Circ. 42147). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ 42159) 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 152 302 147 >19.8 u_FC 311 561 246 >19.1 white 152 5220 220 >19.9 v 641 4360 220 >19.2 b 567 5181 236 >20.3 u 311 4975 462 >19.5 w1 691 4770 216 >19.8 m2 665 4565 216 >19.5 w2 616 810 39 >18.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.786 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42193. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40262] GRB 251010A: Fermi GBM Final Real-time Localization
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42192 SUBJECT: GRB 251010A: Fermi GBM Final Real-time Localization DATE: 25/10/10 17:55:05 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 17:44:25 UT on 10 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251010A (trigger 781811070.725816 / 251010739). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 214.0, Dec = 56.6 (J2000 degrees, equivalent to J2000 14h 16m, 56d 36'), with a statistical uncertainty of 4.5 degrees. The angle from the Fermi LAT boresight is 103.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251010739/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251010739/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251010739/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42192. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40261] GRB251007A: Swift/UVOT Detection
by GCN Circulars 10 Oct '25

10 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42191 SUBJECT: GRB251007A: Swift/UVOT Detection DATE: 25/10/10 17:40:49 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) and E/ Ambrosi (INAF-IASFPA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251007A 79 s after the BAT trigger (Ambrosi et al., GCN Circ. 42146). A fading source consistent with the XRT position (Beardmore et al., GCN Circ. 42161) and the previously reported optical source (Wu et al., GCN Circ. 42154; Malesani et al., GCN Circ. 42158, Hu et al. GCN Circ 42174) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 08:32:42.39 = 128.17664 (deg.) Dec (J2000) = +21:48:46.3 = 21.81285 (deg.) with an estimated uncertainty of 0.45 arc sec. (radius, 90% confidence). Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 80 229 146 18.42+/-0.08 white 17739 18156 406 >20.41 v 11939 39105 2335 >20.09 b 16827 17734 885 >20.39 u 291 418 124 19.11+/-0.36 uvm2 27913 39155 906 >20.29 uvw2 23059 34819 1506 >20.58 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.039 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42191. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0