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[vsnet-grb-info 40676] GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42613 SUBJECT: GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart DATE: 25/11/07 14:32:43 GMT FROM: F. Fortin at IRAP <ffortin.sci.edu(a)gmail.com> Francis Fortin (IRAP), Camila Angulo (UNAM), Jean-Luc Atteia (IRAP), Benjamin Schneider (LAM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the SVOM GRB 251106A (Antier et al., GCN Circ. 42605) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed a second epoch from 2025-11-07 12:34 to 12:50 UTC (from 16.63 to 16.89 hours after the trigger) and obtained an additional 16 minutes of exposure in the r filter at high airmass (3 to 3.5). 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 detect the optical counterpart we previously reported (Angulo et al, GCN Circ. 42607) at the following preliminary magnitude: r = 21.85 +/- 0.13 Our photometry shows clear fading with respect to our earlier epoch, confirming that this is the optical counterpart of the GRB. We note that the position of the afterglow optical counterpart is coincident with a faint source in the Legacy Survey (Dey et al. 2019) at r = 22.56 +/- 0.17, which could be the host galaxy of the GRB. 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/42613. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40675] GRB 251106B: SVOM/GRM observation of a short burst
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42612 SUBJECT: GRB 251106B: SVOM/GRM observation of a short burst DATE: 25/11/07 10:13:32 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: Feliu Lacreu (IAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a burst GRB 251106B (SVOM trigger reference: sb25110603) at 2025-11-06T18:14:44.300 UTC (T0). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple spikes with a T90 of 1.3+0.5/-0.3 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251106B.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/42612. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40674] GRB 251106A: Swift-XRT afterglow detection
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42611 SUBJECT: GRB 251106A: Swift-XRT afterglow detection DATE: 25/11/07 10:12:12 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), S. Lanava (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAR) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of GRB 251106A. We searched for X-ray sources in 2.0 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 2.0 ks, obtained between T0+4.0 ks and T0+9.9 ks. Three uncatalogued X-ray sources are detected, of which one ("Source 1") is above the RASS 3-sigma upper limit at this position, and is therefore likely the GRB afterglow. Using 2020 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 234.46260, +63.36779 which is equivalent to: RA (J2000): 15h 37m 51.02s Dec(J2000): +63d 22' 04.0" with an uncertainty of 2.6 arcsec (radius, 90% confidence). This position is consistent with the optical afterglow candidate identified by Angulo et al. (GCN 42607). The light curve can be modelled with a power-law decay with a decay index of alpha=0.87 (+0.33, -0.29). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.96 (+0.23, -0.22). The best-fitting absorption column is 1.1 (+0.6, -0.5) 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 3.2 x 10^-11 (3.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.1 (+0.6, -0.5) x 10^21 cm^-2 Galactic foreground: 1.7 x 10^20 cm^-2 Excess significance: 2.8 sigma Photon index: 1.96 (+0.23, -0.22) If the light curve continues to decay with a power-law decay index of 0.87, the count rate at T+24 hours will be 0.038 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-12 (1.5 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/03000182. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00048. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42611. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40673] GRB 251106A: Kilonova-Catcher optical upper limit
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42610 SUBJECT: GRB 251106A: Kilonova-Catcher optical upper limit DATE: 25/11/07 08:48:49 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro(a)hotmail.com> M. Freeberg (KNC), D. Turpin (CEA-Saclay/Irfu), C. Andrade(UMN), S. Antier (OCA/IJCLab), M. Coughlin (UMN), S. Karpov (FZU), P. Hello (IJCLAB), M. Pillas (IAP) on behalf of the GRANDMA/Kilonova-Catcher collaboration: We observed the field of GRB 251106A detected by SVOM (Antier et al., GCN 42605), Swift/BAT-GUANO (Delaunay et al., GCN 42608) and Fermi/GBM subthreshold (Godwin et al., GCN 42608) with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with a TEC160FL telescope operated by M. Freeberg. Our observations started at TGRB+5.4hr and were taken with sdss ri filters. In our stacked frames, subtracted from the PanSTARRS DR2 template image, we do not detect the optical counterpart reported by the SVOM/COLIBRI (FM-GFT) (Angulo et al., GCN 42607). We report our follow-up results in the table below: +---------------+-----------+---------+----------------+-------------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | +===============+===========+=========+================+=============+ | 5.77 | 15 x 180s | r (AB) | 19.7 (5 sigma) | TEC160FL | | 6.58 | 15 x 180s | i(AB) | 20.0 (5 sigma) | TEC160FL | +---------------+-----------+---------+----------------+-------------+ All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the sloan filters were calibrated using the PanSTARRS DR1 catalog. We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023). GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42610. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40672] Fermi GBM Sub-Threshold Detection of GRB 251106A
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42609 SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 251106A DATE: 25/11/07 03:05:39 GMT FROM: Matt Godwin <msg0028(a)uah.edu> M. Godwin (UAH) and R. Hamburg (UAH) report on behalf of the Fermi-GBM Team: SVOM/ECLAIRs detected GRB 251106A on 2025-11-06 at 19:56:37 UTC (Antier et al. 2025, GCN 42605). There was no Fermi-GBM onboard trigger around this event time. An automated, blind search for gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified a roughly spatially-consistent candidate at 19:58:18.89 UTC. The GBM Targeted Search [1], the most sensitive coherent search for GRB-like signals in GBM, also identified a transient spatially consistent with GRB 251106A approximately 10 s before the SVOM trigger time. It is detected most significantly ~133 s after the SVOM trigger time on a 4.096 s timescale with a false alarm rate of 3.8e-5 Hz. The event was best-fit using a "normal" GRB spectrum (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3). The Targeted Search localization is consistent with the SVOM/ECLAIRs location. [1] Goldstein et al. 2019 arXiv:1903.12597 View this GCN Circular online at https://gcn.nasa.gov/circulars/42609. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40671] GRB 251106A: Swift/BAT arcminute localization of a burst
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42608 SUBJECT: GRB 251106A: Swift/BAT arcminute localization of a burst DATE: 25/11/07 02:59:54 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Samuele Ronchini (GSSI), Aaron Tohuvavohu (Cosmic Frontier), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 251106A onboard (T0: 2025-11-06T19:56:37 UTC, SVOM/ECLAIRS GCN 42605). In a ground search of a 10 s event file, available due to a subthreshold trigger onboard. The GRB was detected at a S/N of 7.0 in a single 10 s, 15-150 keV image starting at ~T0 + 129 s. The BAT position is RA, Dec = 234.4744, +63.3387 deg which is RA(J2000) = 15h 37m 53.9s Dec(J2000) = +63d 20′ 19.3″ with an estimated uncertainty of 3 arcmin radius. View this GCN Circular online at https://gcn.nasa.gov/circulars/42608. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40670] GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
by GCN Circulars 07 Nov '25

07 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42607 SUBJECT: GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart DATE: 25/11/07 02:38:53 GMT FROM: Camila Angulo Valdez at UNAM <camiangulo(a)astro.unam.mx> Camila Angulo (UNAM), Francis Fortin (IRAP), Jean-Luc Atteia (IRAP), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the SVOM GRB 251106A (Antier et al., GCN Circ. 42605) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-11-07 01:46 to 01:52 UTC (from 5.82 to 5.93 hours after the trigger) and obtained 360 seconds of simultaneous exposure in the r and z filters. The data were analyzed 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 detect an uncatalogued source (revealed by image subtraction using PanSTARRS as template) consistent with the XRT 2.6 arcsec error circle (https://www.swift.ac.uk/SVOM/SVOM_FIELD00048/) at RA, DEC = 234.462239, 63.367568 (J2000) and with preliminary magnitudes of: r = 21.49 +/- 0.10 z = 20.77 +/- 0.13 We suggest this is likely to be the optical counterpart of the GRB. Further observations are ongoing. 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/42607. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40669] GRB 251106A: MASTER optical observations
by GCN Circulars 06 Nov '25

06 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42606 SUBJECT: GRB 251106A: MASTER optical observations DATE: 25/11/06 22:11:56 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.A. Senik, V.M. Lipunov, A.Kuznetsov, E.Gorbovskoy, G.Antipov, 1P.Balanutsa, I.Panchenko, N. Tiurina, K.Zhirkov, Ya.Kechin, A.Chasovnikov, V.Topolev, D.Vlasenko, Yu. Tselik(Lomonosov MSU, SAI, Moscow), R. Podesta, C.Francile, F. Podesta, E. Gonzalez (OAFA, San Juan Uni.,Argentina); D. Buckley (SAAO, South Africa), O. Gress, N.Budnev, O.Ershova (Irkutsk State University), A. Sosnovskij (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) MASTER-Kislovodsk robotic telescope (Global MASTER-Net [1-4], http://observ.pereplet.ru) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of SVOM GRB 251106A (Antier et al. GCN 42605, Ttrigger= 2025-11-06T19:56:37, Tnotice=2025-11-06 20:21:29.84UT) error-box observations 1550 sec after trigger time at 2025-11-06 20:22:27 UT, with upper limit up to 17.9 mag. The observations began 17deg altitude. The sun altitude was -62.3 deg. The galactic latitude b = 45 deg., longitude l = 98 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3034637 There is no optical counterpart withthe following MASTER upper limits upper limits: Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment 1610 | 2025-11-06 20:22:27 | MASTER-Kislovodsk | (15h 37m 28.85s,+63d 06m 03.4s) | P- | 120 | 15.6 | 1750 | 2025-11-06 20:24:47 | MASTER-Kislovodsk | (15h 37m 29.81s,+63d 05m 56.6s) | P- | 120 | 15.6 | 1750 | 2025-11-06 20:24:47 | MASTER-Kislovodsk | (15h 37m 42.69s,+63d 28m 24.2s) | P| | 120 | 17.2 | 1890 | 2025-11-06 20:27:07 | MASTER-Kislovodsk | (15h 37m 30.71s,+63d 05m 51.6s) | P- | 120 | 15.5 | 1890 | 2025-11-06 20:27:07 | MASTER-Kislovodsk | (15h 37m 43.57s,+63d 28m 18.7s) | P| | 120 | 17.3 | 2030 | 2025-11-06 20:29:27 | MASTER-Kislovodsk | (15h 37m 31.56s,+63d 05m 46.7s) | P- | 120 | 15.6 | 2030 | 2025-11-06 20:29:27 | MASTER-Kislovodsk | (15h 37m 44.37s,+63d 28m 13.8s) | P| | 120 | 17.2 | 2140 | 2025-11-06 20:31:47 | MASTER-Kislovodsk | (15h 37m 25.48s,+63d 04m 04.1s) | C | 60 | 17.0 | 2260 | 2025-11-06 20:31:47 | MASTER-Kislovodsk | (15h 37m 25.50s,+63d 04m 04.1s) | C | 300 | 17.5 | Coadd 2140 | 2025-11-06 20:31:47 | MASTER-Kislovodsk | (15h 37m 38.06s,+63d 26m 36.1s) | C | 60 | 17.4 | 2858 | 2025-11-06 20:43:45 | MASTER-Kislovodsk | (15h 36m 59.84s,+63d 06m 24.9s) | C | 60 | 17.0 | 2918 | 2025-11-06 20:43:45 | MASTER-Kislovodsk | (15h 36m 59.83s,+63d 06m 24.9s) | C | 180 | 17.8 | Coadd 2858 | 2025-11-06 20:43:45 | MASTER-Kislovodsk | (15h 37m 12.09s,+63d 29m 02.0s) | C | 60 | 17.4 | 2938 | 2025-11-06 20:45:05 | MASTER-Kislovodsk | (15h 37m 04.06s,+63d 05m 20.5s) | C | 60 | 17.1 | 2938 | 2025-11-06 20:45:05 | MASTER-Kislovodsk | (15h 37m 16.46s,+63d 27m 56.8s) | C | 60 | 17.5 | 3018 | 2025-11-06 20:46:25 | MASTER-Kislovodsk | (15h 36m 58.81s,+63d 04m 17.3s) | C | 60 | 17.0 | 3018 | 2025-11-06 20:46:25 | MASTER-Kislovodsk | (15h 37m 11.34s,+63d 26m 52.9s) | C | 60 | 17.4 | 3128 | 2025-11-06 20:47:45 | MASTER-Kislovodsk | (15h 37m 04.62s,+63d 04m 30.1s) | C | 120 | 17.3 | 3128 | 2025-11-06 20:47:45 | MASTER-Kislovodsk | (15h 37m 17.42s,+63d 27m 05.1s) | C | 120 | 17.4 | 3289 | 2025-11-06 20:50:26 | MASTER-Kislovodsk | (15h 37m 04.51s,+63d 05m 55.6s) | C | 120 | 17.3 | 3289 | 2025-11-06 20:50:26 | MASTER-Kislovodsk | (15h 37m 17.54s,+63d 28m 30.4s) | C | 120 | 17.5 | 3429 | 2025-11-06 20:52:46 | MASTER-Kislovodsk | (15h 37m 05.48s,+63d 04m 10.8s) | C | 120 | 17.2 | 3549 | 2025-11-06 20:52:46 | MASTER-Kislovodsk | (15h 37m 05.48s,+63d 04m 10.8s) | C | 360 | 17.9 | Coadd 3429 | 2025-11-06 20:52:46 | MASTER-Kislovodsk | (15h 37m 18.70s,+63d 26m 45.1s) | C | 120 | 17.5 | 3569 | 2025-11-06 20:55:05 | MASTER-Kislovodsk | (15h 37m 07.60s,+63d 05m 54.6s) | C | 120 | 17.2 | 3569 | 2025-11-06 20:55:05 | MASTER-Kislovodsk | (15h 37m 20.97s,+63d 28m 28.6s) | C | 120 | 17.4 | 3709 | 2025-11-06 20:57:25 | MASTER-Kislovodsk | (15h 37m 04.73s,+63d 05m 01.2s) | C | 120 | 17.2 | 3709 | 2025-11-06 20:57:26 | MASTER-Kislovodsk | (15h 37m 18.15s,+63d 27m 35.0s) | C | 120 | 17.4 | 3849 | 2025-11-06 20:59:45 | MASTER-Kislovodsk | (15h 37m 04.57s,+63d 05m 58.7s) | C | 120 | 17.1 | 3909 | 2025-11-06 20:59:45 | MASTER-Kislovodsk | (15h 37m 04.57s,+63d 05m 58.8s) | C | 240 | 17.5 | Coadd 3849 | 2025-11-06 20:59:45 | MASTER-Kislovodsk | (15h 37m 18.12s,+63d 28m 32.3s) | C | 120 | 17.4 | 3959 | 2025-11-06 21:02:05 | MASTER-Kislovodsk | (15h 37m 10.31s,+63d 04m 57.0s) | C | 60 | 16.8 | 3959 | 2025-11-06 21:02:05 | MASTER-Kislovodsk | (15h 37m 23.89s,+63d 27m 30.6s) | C | 60 | 17.2 | 4039 | 2025-11-06 21:03:25 | MASTER-Kislovodsk | (15h 37m 05.87s,+63d 03m 55.5s) | C | 60 | 16.8 | 4039 | 2025-11-06 21:03:25 | MASTER-Kislovodsk | (15h 37m 19.52s,+63d 26m 29.2s) | C | 60 | 17.2 | 4118 | 2025-11-06 21:04:45 | MASTER-Kislovodsk | (15h 37m 13.13s,+63d 04m 18.9s) | C | 60 | 16.8 | 4178 | 2025-11-06 21:04:45 | MASTER-Kislovodsk | (15h 37m 13.12s,+63d 04m 18.9s) | C | 180 | 17.3 | Coadd 4118 | 2025-11-06 21:04:45 | MASTER-Kislovodsk | (15h 37m 26.81s,+63d 26m 52.7s) | C | 60 | 17.1 | Observations and data analysis will be continued. [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/42606. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40668] GRB 251106A: SVOM detection of a burst
by GCN Circulars 06 Nov '25

06 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42605 SUBJECT: GRB 251106A: SVOM detection of a burst DATE: 25/11/06 20:37:09 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> S. Antier (IJCLAB), M. Dennefeld (IAP), S. Schanne (CEA/Irfu), F. Lacreu (IAP) report on behalf of the SVOM mission team: At 2025-11-06T19:56:37 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251106A (SVOM burst-id sb25110604). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 16 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 11.02 in the [8-120] keV energy band over a time window of 163.84 seconds starting at 2025-11-06T19:55:40. The localization of the best alert is R.A., Dec. 234.6169, 63.3716 degrees: R.A. (J2000) = 15h38m28.05s Dec. (J2000) = 63d22m17.83s with a 90% confidence level (C.L.) radius of 7.27 arcmin (including systematic error of 2 arcmin added in quadrature). Due to sun constraints, no immediate slew was performed on this burst. No X-ray observation could be performed by SVOM/MXT for the time being. No optical observation could be performed by SVOM/VT for the time being. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Sarah Antier: sarah.antier(a)ijclab.in2p3.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42605. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40667] GRB 251103B: AstroSat CZTI detection
by GCN Circulars 06 Nov '25

06 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42604 SUBJECT: GRB 251103B: AstroSat CZTI detection DATE: 25/11/06 19:18:43 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 long GRB 251103B which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42555), and Swift BAT (Lanava et. al., GCN Circ. 42556). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-11-03 16:46:36.50 UTC. The measured peak count rate associated with the burst is 87 (+31, -16) counts/s above the background in the combined data of three quadrants (out of four), with a total of 307 (+118, -98) counts. We caution that there is a 0.3 s readout dead time in CZT data during the burst which affects the calculated total counts. The local mean background count rate was 215 (+2, -4) counts/s. Using cumulative rates, we measure a T90 of 5.86 (+0.85, -2.24) s. The source was also faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-03 16:46:41.66 UTC. The measured peak count rate associated with the burst is 148 (+74, -23) counts/s above the background in the combined data of all quadrants, with a total of 677 (+244, -247) counts. The local mean background count rate was 1281 (+6, -7) counts/s. Due to poor statistics, we cannot reliably estimate the 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/42604. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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