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

[vsnet-grb-info 40410] GRB 251013C: Liverpool Telescope observations
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42334 SUBJECT: GRB 251013C: Liverpool Telescope observations DATE: 25/10/17 21:03:54 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek and D. A. Perley (LJMU) report: We observed the field of GRB 251013C (Fermi GBM team, GCN 42221; Rakotondrainibe et al., GCN 42222) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 60s exposures in the SDSS ugriz filters, starting on 2025-10-14 01:46:49, about 8.1h after Fermi trigger. We report detections in all bands, at the position of the optical afterglow first reported by Palmerio et al., GCN 42223: MJD (start) T_mid-T_0 Filter Mag. (AB) 60962.07711 8.20 h u 19.07 ± 0.10 60962.07418 8.13 h g 18.62 ± 0.04 60962.07517 8.15 h r 18.36 ± 0.02 60962.07614 8.17 h i 18.14 ± 0.03 60962.07877 8.24 h z 18.00 ± 0.03 The photometry for griz filters was calibrated using nearby PanSTARRS secondary standards, while u-band photometry was calibrated using the SDSS catalogue. The photometry is not corrected for extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42334. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40409] GRB 251013C: Leavitt Observatory optical photometry
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42333 SUBJECT: GRB 251013C: Leavitt Observatory optical photometry DATE: 25/10/17 20:56:44 GMT FROM: leavittob(a)gmail.com E. Pavoni, L. Moretti (Leavitt Observatory, Italy) Members of: GRB/UAI - Gamma Ray Burst Section of Unione Astrofili Italiani In a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), report: We performed a follow-up observation of the field of GRB 251013C (Fermi GBM team, GCN 42221; Rakotondrainibe et al., GCN 42222) using our 250mm f/8 Ritchey-Chrétien telescope (Leavitt Observatory, Manciano, Italy). Observations began on 2025-10-13 at 19:09:11 UT (≈ 1.5 hours after the trigger) and ended at 22:19:55 UT. A series of images in Rc and Ic filter (Johnson-Cousins system) was obtained under good weather conditions. We clearly detected a bright afterglow positionally consistent with the source reported in previous circulars. The OT coordinates are: RA (J2000) = 23:03:20.55 Dec(J2000) = -00:12:35.12 (±2 arcsec on both axes) Photometry was performed using nearby stars from the Pan-STARRS catalog (magnitudes converted using Lupton (2005) equations) and analysed with AstroImageJ (2017AJ....153...77C). The following magnitudes were measured (not corrected for Galactic extinction): HJD at mid-exposure Filter Mag. Mag. err. 2460962.30386029 Rc 15.38 0.01 2460962.30725948 Rc 15.51 0.01 2460962.30996796 Rc 15.67 0.01 2460962.31258558 Rc 15.73 0.02 2460962.31556121 Rc 15.74 0.02 2460962.31806558 Rc 15.76 0.02 2460962.32017580 Rc 15.86 0.02 2460962.32228375 Rc 15.84 0.02 2460962.32439216 Rc 15.84 0.02 2460962.32650057 Rc 15.89 0.02 2460962.32860895 Rc 15.90 0.02 2460962.33071795 Rc 15.92 0.02 2460962.33282552 Rc 15.97 0.02 2460962.33493454 Rc 15.96 0.02 2460962.33704239 Rc 16.04 0.02 2460962.33915074 Rc 16.12 0.02 2460962.34126105 Rc 16.12 0.02 2460962.34337272 Rc 16.19 0.02 2460962.34548188 Rc 16.27 0.02 2460962.34759218 Rc 16.29 0.02 2460962.35500912 Rc 16.33 0.02 2460962.35926398 Rc 16.34 0.02 2460962.36351931 Rc 16.37 0.02 2460962.36777694 Rc 16.41 0.02 2460962.37203488 Rc 16.56 0.03 2460962.37629036 Rc 16.46 0.03 2460962.38920934 Rc 16.64 0.03 2460962.39346447 Rc 16.54 0.03 2460962.39772065 Rc 16.69 0.03 2460962.40623373 Rc 16.80 0.04 2460962.41049247 Rc 16.75 0.03 2460962.41474858 Rc 16.93 0.04 2460962.41900117 Rc 16.82 0.04 2460962.42325452 Rc 16.72 0.04 2460962.42750818 Rc 17.11 0.05 2460962.35287059 Ic 15.94 0.03 2460962.35712512 Ic 15.95 0.03 2460962.36138024 Ic 15.92 0.03 2460962.36563799 Ic 15.86 0.03 2460962.36989563 Ic 16.05 0.04 2460962.37415044 Ic 16.25 0.04 2460962.38706915 Ic 16.14 0.04 2460962.39132719 Ic 16.19 0.04 2460962.39558282 Ic 16.33 0.05 2460962.39983877 Ic 16.23 0.05 2460962.40409469 Ic 16.37 0.05 2460962.40835283 Ic 16.40 0.05 2460962.41261135 Ic 16.43 0.06 2460962.41686396 Ic 16.24 0.05 2460962.42111700 Ic 16.42 0.06 2460962.42537095 Ic 16.49 0.06 2460962.42997457 Ic 16.68 0.07 2460962.43422909 Ic 16.63 0.07 This message may be cited. Reference: https://leavittobservatory.altervista.org View this GCN Circular online at https://gcn.nasa.gov/circulars/42333. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40408] Fermi GRB 251016B: Global MASTER-Net observations report
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42332 SUBJECT: Fermi GRB 251016B: Global MASTER-Net observations report DATE: 25/10/17 20:01:03 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 251016B ( Fermi GBM team, GCN 42316) errorbox 64428 sec after notice time and 64463 sec after trigger time at 2025-10-17 17:53:24 UT, with upper limit up to 18.4 mag. The observations began at zenith distance = 75 deg. The sun altitude is -38.0 deg. The galactic latitude b = 57 deg., longitude l = 131 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3016439 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 64493 | 2025-10-17 17:53:24 | MASTER-Kislovodsk | (12h 10m 29.71s , +59d 47m 44.4s) | C | 60 | 17.9 | 64493 | 2025-10-17 17:53:24 | MASTER-Kislovodsk | (12h 02m 34.87s , +60d 07m 45.3s) | C | 60 | 18.2 | 64573 | 2025-10-17 17:54:44 | MASTER-Kislovodsk | (11h 59m 57.83s , +57d 53m 49.9s) | C | 60 | 17.7 | 64653 | 2025-10-17 17:56:03 | MASTER-Kislovodsk | (12h 28m 38.77s , +57d 56m 06.7s) | C | 60 | 17.7 | 64653 | 2025-10-17 17:56:03 | MASTER-Kislovodsk | (12h 21m 10.62s , +58d 16m 11.0s) | C | 60 | 17.9 | 64733 | 2025-10-17 17:57:23 | MASTER-Kislovodsk | (12h 23m 18.88s , +61d 41m 55.2s) | C | 60 | 17.6 | 64733 | 2025-10-17 17:57:23 | MASTER-Kislovodsk | (12h 14m 53.21s , +62d 01m 54.8s) | C | 60 | 18.2 | 64976 | 2025-10-17 18:01:26 | MASTER-Kislovodsk | (12h 32m 54.86s , +60d 10m 17.7s) | C | 60 | 18.2 | 65135 | 2025-10-17 18:04:06 | MASTER-Kislovodsk | (12h 10m 31.27s , +59d 47m 15.5s) | C | 60 | 17.9 | 65135 | 2025-10-17 18:04:06 | MASTER-Kislovodsk | (12h 02m 38.29s , +60d 07m 24.6s) | C | 60 | 18.4 | 65216 | 2025-10-17 18:05:26 | MASTER-Kislovodsk | (12h 00m 00.77s , +57d 53m 08.9s) | C | 60 | 17.6 | 65296 | 2025-10-17 18:06:46 | MASTER-Kislovodsk | (12h 28m 41.30s , +57d 55m 38.0s) | C | 60 | 17.6 | 65296 | 2025-10-17 18:06:46 | MASTER-Kislovodsk | (12h 21m 14.36s , +58d 15m 48.0s) | C | 60 | 18.0 | 65781 | 2025-10-17 18:14:51 | MASTER-Kislovodsk | (12h 23m 20.47s , +61d 42m 21.0s) | C | 60 | 17.6 | 65781 | 2025-10-17 18:14:52 | MASTER-Kislovodsk | (12h 14m 56.78s , +62d 02m 32.5s) | C | 60 | 18.1 | 66021 | 2025-10-17 18:18:52 | MASTER-Kislovodsk | (12h 33m 02.17s , +60d 07m 57.4s) | C | 60 | 18.1 | 66181 | 2025-10-17 18:21:31 | MASTER-Kislovodsk | (12h 10m 40.13s , +59d 48m 37.0s) | C | 60 | 17.9 | 66181 | 2025-10-17 18:21:31 | MASTER-Kislovodsk | (12h 02m 49.68s , +60d 08m 56.5s) | C | 60 | 18.3 | 66261 | 2025-10-17 18:22:51 | MASTER-Kislovodsk | (12h 00m 02.22s , +57d 53m 04.0s) | C | 60 | 17.6 | 66341 | 2025-10-17 18:24:11 | MASTER-Kislovodsk | (12h 28m 46.58s , +57d 54m 54.8s) | C | 60 | 17.6 | 66341 | 2025-10-17 18:24:12 | MASTER-Kislovodsk | (12h 21m 22.73s , +58d 15m 14.6s) | C | 60 | 17.9 | 66632 | 2025-10-17 18:29:02 | MASTER-Kislovodsk | (12h 23m 25.23s , +61d 42m 58.9s) | C | 60 | 17.7 | 66632 | 2025-10-17 18:29:02 | MASTER-Kislovodsk | (12h 15m 03.72s , +62d 03m 15.8s) | C | 60 | 18.1 | 67078 | 2025-10-17 18:36:28 | MASTER-Kislovodsk | (12h 33m 12.10s , +60d 09m 22.3s) | C | 60 | 18.1 | 67237 | 2025-10-17 18:39:07 | MASTER-Kislovodsk | (12h 10m 48.06s , +59d 48m 19.7s) | C | 60 | 17.9 | 67237 | 2025-10-17 18:39:08 | MASTER-Kislovodsk | (12h 02m 58.20s , +60d 08m 43.5s) | C | 60 | 18.1 | 67317 | 2025-10-17 18:40:27 | MASTER-Kislovodsk | (12h 00m 05.23s , +57d 53m 23.6s) | C | 60 | 17.6 | 67397 | 2025-10-17 18:41:47 | MASTER-Kislovodsk | (12h 28m 47.12s , +57d 54m 50.5s) | C | 60 | 17.6 | 67397 | 2025-10-17 18:41:47 | MASTER-Kislovodsk | (12h 21m 23.71s , +58d 15m 15.1s) | C | 60 | 18.0 | 67687 | 2025-10-17 18:46:37 | MASTER-Kislovodsk | (12h 23m 27.68s , +61d 40m 36.8s) | C | 60 | 17.6 | 67687 | 2025-10-17 18:46:37 | MASTER-Kislovodsk | (12h 15m 10.60s , +62d 00m 56.4s) | C | 60 | 18.1 | 67926 | 2025-10-17 18:50:37 | MASTER-Kislovodsk | (12h 33m 18.29s , +60d 07m 34.3s) | C | 60 | 18.1 | 68293 | 2025-10-17 18:56:43 | MASTER-Kislovodsk | (12h 10m 54.87s , +59d 48m 17.3s) | C | 60 | 17.9 | 68293 | 2025-10-17 18:56:43 | MASTER-Kislovodsk | (12h 02m 59.73s , +60d 08m 46.1s) | C | 60 | 18.2 | 68373 | 2025-10-17 18:58:03 | MASTER-Kislovodsk | (12h 00m 24.20s , +57d 53m 11.7s) | C | 60 | 17.6 | 68452 | 2025-10-17 18:59:23 | MASTER-Kislovodsk | (12h 28m 56.85s , +57d 52m 31.8s) | C | 60 | 17.6 | 68453 | 2025-10-17 18:59:23 | MASTER-Kislovodsk | (12h 21m 29.31s , +58d 13m 01.5s) | C | 60 | 17.9 | 68753 | 2025-10-17 19:04:23 | MASTER-Kislovodsk | (12h 23m 37.61s , +61d 41m 55.7s) | C | 60 | 17.6 | 68754 | 2025-10-17 19:04:24 | MASTER-Kislovodsk | (12h 15m 21.05s , +62d 02m 17.0s) | C | 60 | 18.1 | 68994 | 2025-10-17 19:08:25 | MASTER-Kislovodsk | (12h 33m 21.64s , +60d 08m 01.0s) | C | 60 | 18.1 | 69157 | 2025-10-17 19:11:08 | MASTER-Kislovodsk | (12h 10m 49.35s , +59d 47m 14.2s) | C | 60 | 17.6 | 69157 | 2025-10-17 19:11:08 | MASTER-Kislovodsk | (12h 03m 11.06s , +60d 07m 42.8s) | C | 60 | 18.2 | 69445 | 2025-10-17 19:15:56 | MASTER-Kislovodsk | (12h 00m 15.93s , +57d 52m 23.4s) | C | 60 | 17.6 | 69525 | 2025-10-17 19:17:15 | MASTER-Kislovodsk | (12h 28m 54.84s , +57d 54m 20.9s) | C | 60 | 17.5 | 69525 | 2025-10-17 19:17:15 | MASTER-Kislovodsk | (12h 21m 39.39s , +58d 14m 53.4s) | C | 60 | 18.1 | 69815 | 2025-10-17 19:22:05 | MASTER-Kislovodsk | (12h 23m 48.31s , +61d 42m 05.7s) | C | 60 | 17.6 | 69815 | 2025-10-17 19:22:05 | MASTER-Kislovodsk | (12h 15m 32.13s , +62d 02m 32.5s) | C | 60 | 18.0 | 69975 | 2025-10-17 19:24:45 | MASTER-Kislovodsk | (11h 58m 36.13s , +61d 27m 27.6s) | C | 60 | 17.9 | 70055 | 2025-10-17 19:26:05 | MASTER-Kislovodsk | (12h 33m 35.77s , +60d 07m 51.8s) | C | 60 | 17.9 | 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/42332. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40407] GRB 251017A: JinShan observations of the optical afterglow
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42331 SUBJECT: GRB 251017A: JinShan observations of the optical afterglow DATE: 25/10/17 18:35:37 GMT FROM: syfu(a)nao.cas.cn S.Y. Fu (HUST), L.B. He, X. Liu, J. An, S.Q. Jiang, Z.P. Zhu, D. Xu (NAOC), A.D. Zhu, L. Lei, H.Z. Wu (HUST), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the field of Swift GRB 251017A (Gupta et al., GCN 42322) using the 100C telescope of the JinShan project, located at Altay, Xinjiang, China. Observations started at 2025-10-17 12:50:19.42 UT, i.e., 4.16 hours after the trigger, and a series of 300s frames in r and z bands were obtained. The previously reported optical afterglow (Perez-Garcia et al., GCN 42323; Antier et al., GCN 42325; Sasada et al., GCN 42329) was clearly detected in our images with r-band magnitude r = 21.17 +- 0.06, calibrated with nearby Pan-STARRS1 DR2 catalog and without the Galactic extinction correction. We acknowledge the excellent support from T.Q. Chen and J.F. Zhang for enabling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42331. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40406] Swift GRB 251017A: Global MASTER-Net observations report
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42330 SUBJECT: Swift GRB 251017A: Global MASTER-Net observations report DATE: 25/10/17 16:16:40 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 251017A ( R. Gupta et al., GCN 42322) errorbox 26422 sec after notice time and 26441 sec after trigger time at 2025-10-17 16:01:26 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 43 deg. The sun altitude is -18.3 deg. The galactic latitude b = -40 deg., longitude l = 72 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3016699 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 26532 | MASTER-Kislovodsk | C | 180 | 12.8 | 26532 | MASTER-Kislovodsk | C | 180 | 17.9 | 26731 | MASTER-Kislovodsk | C | 180 | 13.4 | 26732 | MASTER-Kislovodsk | C | 180 | 17.9 | 26931 | MASTER-Kislovodsk | C | 180 | 13.0 | 26932 | MASTER-Kislovodsk | C | 180 | 17.9 | 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/42330. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40405] GRB 251017A : MITSuME Akeno optical afterglow candidate detection
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42329 SUBJECT: GRB 251017A : MITSuME Akeno optical afterglow candidate detection DATE: 25/10/17 16:06:04 GMT FROM: Mahito Sasada at Tokyo Institute of Technology <sasada(a)hp.phys.titech.ac.jp> M. Sasada, A. Ochi, R. Kato, Y. Kubo, H. Hagio, H. Seki, S. Joshima, I. Takahashi, Y. Yatsu and N. Kawai (Science Tokyo) report on behalf of the MITSuME collaboration: We observed the field of GRB 251017A detected by Swift/BAT (Gupta et al. GCN 42322) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno. The observation started at 2025-10-17 08:41:53 UT (69 seconds after the Swift/BAT trigger). We stacked the images with good conditions. We detected a point source in the Ic-band image at a position of the reported optical candidate (Gupta et al. GCN 42322; Perez-Garcia et al. GCN 42323; Antier et al. GCN 42325). Here we report the magnitude of the source as follows. T0+[sec] | MID-UT | T-EXP[sec] | magnitude ------------------------------------------------------------------------------------------------ 9256 | 2025-10-17 11:15:00 | 11520 | Ic=19.7+/-0.2 ------------------------------------------------------------------------------------------------ T0+ : Elapsed time after the trigger T-EXP: Total Exposure time We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ; https://github.com/MNiwano/Eclaire) View this GCN Circular online at https://gcn.nasa.gov/circulars/42329. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40404] Swift Trigger 1404295 is not a GRB
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42328 SUBJECT: Swift Trigger 1404295 is not a GRB DATE: 25/10/17 15:26:20 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> R. Gupta (NASA GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII), D. M. Palmer (LANL), and T. Sbarrato (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: Using the data set from T-183 to T+963 sec from telemetry downlinks, we report further analysis of BAT trigger #1404295 (Klingler, et al., GCN Circ. 42290). This trigger is due to noise in the BAT image domain, with no significant emission detected in the mask-weighted light curve. No confirmed counterpart is found in the XRT or UVOT data within the BAT error circle, indicating that the trigger is not a real astrophysical event. View this GCN Circular online at https://gcn.nasa.gov/circulars/42328. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40403] GRB 251016A: AstroSat CZTI detection of a short burst
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42327 SUBJECT: GRB 251016A: AstroSat CZTI detection of a short burst DATE: 25/10/17 13:05:35 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Goyal (IITB), A. Arya (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 a short-duration GRB 251016A which was also detected by SVOM/ECLAIRs (Basa et al., GCN Circ. 42308), Fermi GBM (Fermi GBM Team, GCN Circ. 42309), Glowbug (Woolf et al., GCN Circ. 42313) and CALET GBM (Kawakubo et al., GCN Circ. 42321). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-10-16 14:59:16.90 UTC. The measured peak count rate associated with the burst is 1142 (+782, -64) counts/s above the background in the combined data of all four quadrants, with a total of 140 (+39, -30) counts. The local mean background count rate was 264 (+14, -45) counts/s. Using cumulative rates, we measure a T90 of 0.31 (+0.04, -0.08) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-10-16 14:59:16.68 UTC. The measured peak count rate associated with the burst is 1099 (+76, -82) counts/s above the background in the combined data of all quadrants, with a total of 1056 (+117, -126) counts. The local mean background count rate was 1232 (+9, -10) counts/s. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 from it. 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/42327. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40402] GRB 251017A: Enhanced Swift-XRT position
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42326 SUBJECT: GRB 251017A: Enhanced Swift-XRT position DATE: 25/10/17 12:54:56 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 1230 s of XRT Photon Counting mode data and 2 UVOT images for GRB 251017A, 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 = 335.40133, +7.04008 which is equivalent to: RA (J2000): 22h 21m 36.32s Dec (J2000): +07d 02' 24.3" with an uncertainty of 2.1 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/42326. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40401] GRB 251017A: COLIBRÍ Early Afterglow Detection
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42325 SUBJECT: GRB 251017A: COLIBRÍ Early Afterglow Detection DATE: 25/10/17 11:03:48 GMT FROM: Dalya Akl at American Uni. SHJ <dalyaakl.d(a)gmail.com> Sarah Antier (IJCLAB), Dalya Akl (NYUAD), Enrique Moreno Méndez (UNAM), Alan M. Watson (UNAM), Noémie Globus (UNAM), Ny Avo Rakotondrainibe (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU) , Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the Swift GRB 251017A (Page et al., GCN Circ. 42322) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-10-17 08:41 to 09:15 UTC (from 1 min to 35 min after the trigger) and obtained 35 minutes of simultaneous exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We detected the optical counterpart reported by Page et al., GCN Circ. 4232, at the SVOM/UVOT, with preliminary magnitudes of our first images: r = 19.90 +/- 0.17 z = 17.94 +/- 0.09 We note that the r-z color is ~2 mag. Concurrent observations were taken by BOOTES (I. Perez-Garcia et al., 42323). Further observations in g/r/i/z/y are planned. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/42325. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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