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

[vsnet-grb-info 40414] GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42338 SUBJECT: GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening DATE: 25/10/17 21:44:41 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> C. Adami (LAM/Pytheas/AMU), N.A. Rakotondrainibe (LAM), E. Le Floc'h (CEA/Irfu), S. Basa (Pytheas/OHP/LAM), B. Schneider (LAM), report on behalf of the MISTRAL GRB collaboration: We carried out further observations of the GRB 251013C optical, NIR, and radio afterglow (Palmerio et al., GCN 42223 ; Perez-Garcia et al., GCN 42225 ; Konno et al., GCN 42226 ; Martin-Carrillo et al., GCN 42227 ; Masi et al., GCN 42228 ; Palmerio et al., GCN 42229 ; Moskvitin et al., GCN 42230 ; Gompertz et al., GCN 42231 ; Lipunov et al., GCN 42235 ; Garnavich, GCN42240; Watson et al., GCN 42241 ; Lopez-Camara et al., GCN 42242 ; Laskar et al., GCN 42243; Zhang et al., GCN 42248; Brosio et al., GCN 42251; Reguitti et al., GCN 42253 ; Quintana-Ansaldo et al., GCN 42254; Maksut et al., GCN 42256; Ghosh et al., GCN 42261 ; Quadri et al., GCN 42262 ; Adami et al. GCN 42266 ; Peretto et al., GCN 42267 ; Ruocco et al., GCN 42269 ; Calapai, GCN 42275; Adami et al., GCN 42276; Globus et al., GCN 42279; Abidkhanov et al., 42283; Rhodes et al., GCN 42294; Siegel et al., GCN 42298; Leonini et al., GCN 42301; Christy et al., GCN 42312; Moreno Méndez et al., GCN 42318; He et al., GCN 42319; Pavoni et al., GCN 42333; Bochenek et al., GCN 42334) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 4 exposures of 10min in the r-band at a mid time of 2025-10-17 19:05:33UT, corresponding to T-T0 = 97.43 hr. The afterglow is well detected and we measured the following preliminary magnitude: r’ = 20.74+/-0.06 mag (AB) This clearly shows a rebrightening as compared to our second epoch observations (r’ = 21.29 +/- 0.07), consistently with the results of Moreno Méndez et al. (GCN 42318). The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitudes are not corrected for Galactic extinction. We used the STDWeb/STDPipe tools (Karpov 2025). We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Yoann Degot-longhi and the SOPHIE observers H. Bouy View this GCN Circular online at https://gcn.nasa.gov/circulars/42338. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40413] LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42337 SUBJECT: LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate DATE: 25/10/17 21:38:45 GMT FROM: shoki.iwaguchi(a)ligo.org The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: The trigger S251017di is no longer considered to be a candidate of interest. This candidate was initially identified by one or more early-warning analyses by matching partial signal templates to the data. Analysis of additional data up to the putative merger time, with full signal templates, did not make a significant detection, indicating that the initial candidate was likely due to transient noise. View this GCN Circular online at https://gcn.nasa.gov/circulars/42337. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40412] GRB 251017A: J-band detection with WINTER
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42336 SUBJECT: GRB 251017A: J-band detection with WINTER DATE: 25/10/17 21:17:36 GMT FROM: Geoffrey Mo at Caltech / Carnegie Observatories <gmo(a)mit.edu> Geoffrey Mo (Caltech/Carnegie), Tomas Ahumada (Caltech), Viraj Karambelkar (Columbia), Benjamin Schneider (LAM), Robert Stein (UMD), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report: We observed the field of GRB 251017A (Gupta et al., GCN 42322; Goad et al., GCN 42326; Woolf et al., GCN 42335) in the near-infrared J band with the Palomar 1-m telescope, equipped with the 1.2-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024). Observations began at 2025-10-17T09:01:23 UTC in the J band (~21 minutes after the GRB trigger), consisting of 15 x 120 s exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565). We detect a clear source at the optical counterpart location (Gupta et al., GCN 42322; Perez-Garcia et al., GCN 42323; Antier et al., GCN 42325; Sasada et al., GCN 42329; Lipunov et al., GCN 42330; Fu et al., GCN 42331), with magnitude J ~ 18.7 mag (AB). WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research. View this GCN Circular online at https://gcn.nasa.gov/circulars/42336. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40411] GRB 251017A: Glowbug gamma-ray detection
by GCN Circulars 17 Oct '25

17 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42335 SUBJECT: GRB 251017A: Glowbug gamma-ray detection DATE: 25/10/17 21:06:38 GMT FROM: richard.s.woolf.civ(a)us.navy.mil R. Woolf, C.C. Cheung, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251017A, which was also detected by Swift/BAT (GCN 42322). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-10-17 08:40:42.816 with a duration of 8.2 s and a total significance of about 11.9 sigma. The light curve comprises two primary peaks. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS, and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42335. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[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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