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[vsnet-grb-info 40925] GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
by GCN Circulars 27 Nov '25

27 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42856 SUBJECT: GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory DATE: 25/11/27 06:40:21 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> M. Pulido-Torres, J. Basurto Merino, P.G. Berdayes, A. Caballero-Almagro, A. Cerón, M. Contreras, F. Díaz-Segado, T. Ferrer-Laviña, B. Gandolfi, V. Ghiraldo, J. Hernández Fung, L. Juliá-Maroto, E. Lekaroz-Urriza, M. Manzano García, E. Mejía-Martínez, J. Prieto Polo, M. Quintana-Ansaldo, A. Schenone-Zanuzzi, A. Selezneva, T. Tundidor Rodríguez, E. Urquijo-Rodríguez (all ULL), M. Abdul-Masih (IAC and ULL), and I. Pérez-Fournon (IAC and ULL). Following the detection of the Swift GRB 251126A (Caputo et al., GCN Circ. 42843; Evans et al., GCN Circ. 42845; and Goad et al., GCN Circ. 42851), we observed the field with one of the two Las Cumbres Observatory (LCO) 1-m telescopes equipped with Sinistro cameras located at the LCO node at McDonald Observatory, Texas. The observation, a single exposure of 300 sec in the SDSS r' filter, started on 2025-11-27 at 04:41:19 UT, about 9.51 hours after the Swift trigger. The optical counterpart first detected by the GROWTH-India Telescope (GIT) (Swain et al., GCN Circ. 42844) is clearly detected in our image with a magnitude of r' = 20.86 +/- 0.13 (AB), calibrated against PanSTARRS-1 DR2 stars and not corrected for Galactic extinction. Our result is consistent with other optical observations: Swain et al. (GCN Circ. 42844), Lipunov et al. (GCN Circ. 42847), Fu et al. (GCN Circ. 42848), Reguitti et al. (GCN Circ. 42849), Broens et al. (GCN Circ. 42850), and Angulo et al. (GCN Circ. 42855). This work makes use of observations from the Las Cumbres Observatory global telescope network (LCO program IAC2025B-010). These observations are part of a course in Astrophysical Techniques of the Master in Astrophysics of the Astrophysics Department of the University of La Laguna in collaboration with the Instituto de Astrofísica de Canarias (La Laguna, Tenerife, Canary Islands, Spain). This work made use of the Astro-COLIBRI platform (P. Reichherzer et al. 2021, ApJS, 256, 5). View this GCN Circular online at https://gcn.nasa.gov/circulars/42856. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40924] GRB 251126A: COLIBRÍ photometric redshift z = 3.5
by GCN Circulars 27 Nov '25

27 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42855 SUBJECT: GRB 251126A: COLIBRÍ photometric redshift z = 3.5 DATE: 25/11/27 04:57:59 GMT FROM: Camila Angulo Valdez at UNAM <camiangulo(a)astro.unam.mx> Camila Angulo (UNAM), Ny Avo Rakotondrainibe (LAM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), 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), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the Swift GRB 251126A (Caputo et al., GCN Circ. 42843) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-11-27 02:49 to 04:14 UTC (from 7.6 to 9.1 hours after the trigger) and obtained, respectively, 10, 27, 11, 23, and 23 minutes of exposure in the g, r, i, z, and y filters. The data were reduced, coadded, and analyzed with the ASU pipeline. 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 Swain et al. (GCN Circ. 42844), Lipunov et al. (GCN Circ. 42847), Fu et al. (GCN Circ. 42848), Reguitti et al. (GCN Circ. 42849), and Broens et al. (GCN Circ. 42850) at preliminary magnitudes of: r = 20.62 +/- 0.05 z = 19.86 +/- 0.07 In our data, we see a clear break in the spectrum in g. After correcting for the Galactic foreground extinction corresponding to a reddening of E(B-V) = 0.063 mag (Schlafly & Finkbeiner 2011) and fitting a power-law model to the grizy-bands with SMC extinction, we derive a photometric redshift of z = 3.52 (+0.18, -0.20, 1-sigma confidence interval). 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/42855. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40923] GRB 251125B: GECAM-B detection
by GCN Circulars 27 Nov '25

27 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42854 SUBJECT: GRB 251125B: GECAM-B detection DATE: 25/11/27 04:41:58 GMT FROM: renyz16607(a)163.com Yang-Zhao Ren, Chen-Wei Wang, Chao Zheng, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by a long burst, GRB 251125B, at 2025-11-25T20:23:45.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #42836). According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of a pulse with a duration (T90) of 8.5 +2.0/-3.5 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251125B.png The time-averaged spectrum from T0-0.8 s to T0+9.3 s is best fitted by a power law function. The power law index is -1.36 +0.06/-0.05. The event fluence (10-1000 keV) in this time interval is (2.86 +0.34/-0.31)E-06 erg/cm^2. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/42854. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40922] Fermi GRB 251127A: Global MASTER-Net observations report
by GCN Circulars 27 Nov '25

27 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42853 SUBJECT: Fermi GRB 251127A: Global MASTER-Net observations report DATE: 25/11/27 03:30:35 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 [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 251127A ( Fermi GBM team, GCN 42852) errorbox 26 sec after notice time and 61 sec after trigger time at 2025-11-27 03:18:44 UT, with upper limit up to 16.6 mag. Observations started at twilight. The observations began at zenith distance = 14 deg. The sun altitude is -10.6 deg. The galactic latitude b = 58 deg., longitude l = 199 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3052815 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 67 | 2025-11-27 03:18:44 | MASTER-Kislovodsk | (10h 26m 49.07s , +29d 21m 07.8s) | C | 10 | 15.7 | 67 | 2025-11-27 03:18:44 | MASTER-Kislovodsk | (10h 21m 41.55s , +29d 42m 18.9s) | C | 10 | 14.2 | 96 | 2025-11-27 03:19:13 | MASTER-Kislovodsk | (10h 26m 49.14s , +29d 21m 07.1s) | C | 10 | 15.7 | 96 | 2025-11-27 03:19:14 | MASTER-Kislovodsk | (10h 21m 41.27s , +29d 42m 13.3s) | C | 10 | 14.1 | 144 | 2025-11-27 03:19:52 | MASTER-Kislovodsk | (10h 28m 11.83s , +32d 30m 38.8s) | C | 30 | 16.6 | 144 | 2025-11-27 03:19:52 | MASTER-Kislovodsk | (10h 22m 52.53s , +32d 52m 02.7s) | C | 30 | 15.4 | 194 | 2025-11-27 03:20:42 | MASTER-Kislovodsk | (10h 22m 52.49s , +32d 52m 02.0s) | C | 30 | 15.2 | 194 | 2025-11-27 03:20:42 | MASTER-Kislovodsk | (10h 28m 11.82s , +32d 30m 38.3s) | C | 30 | 16.4 | 249 | 2025-11-27 03:21:31 | MASTER-Kislovodsk | (10h 22m 52.28s , +32d 51m 59.6s) | C | 40 | 15.4 | 249 | 2025-11-27 03:21:31 | MASTER-Kislovodsk | (10h 28m 11.77s , +32d 30m 37.9s) | C | 40 | 16.6 | 314 | 2025-11-27 03:22:31 | MASTER-Kislovodsk | (10h 28m 11.71s , +32d 30m 37.2s) | C | 50 | 16.4 | 314 | 2025-11-27 03:22:31 | MASTER-Kislovodsk | (10h 22m 52.22s , +32d 51m 59.0s) | C | 50 | 15.1 | 394 | 2025-11-27 03:23:41 | MASTER-Kislovodsk | (10h 22m 51.99s , +32d 51m 57.2s) | C | 70 | 15.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42853. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40921] GRB 251127A: Fermi GBM Final Real-time Localization
by GCN Circulars 27 Nov '25

27 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42852 SUBJECT: GRB 251127A: Fermi GBM Final Real-time Localization DATE: 25/11/27 03:28:10 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 03:17:42 UT on 27 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251127A (trigger 785906267.770746 / 251127137). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 155.6, Dec = 30.2 (J2000 degrees, equivalent to J2000 10h 22m, 30d 11'), with a statistical uncertainty of 4.1 degrees. The angle from the Fermi LAT boresight is 24.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251127137/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251127137/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251127137/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42852. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40920] GRB 251126A: Enhanced Swift-XRT position
by GCN Circulars 27 Nov '25

27 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42851 SUBJECT: GRB 251126A: Enhanced Swift-XRT position DATE: 25/11/27 01:31:57 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 633 s of XRT Photon Counting mode data and 1 UVOT images for GRB 251126A, 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 = 99.94120, +54.98588 which is equivalent to: RA (J2000): 06h 39m 45.89s Dec (J2000): +54d 59' 09.2" with an uncertainty of 4.5 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/42851. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40919] GRB 251126A: Kilonova-Catcher optical afterglow detection
by GCN Circulars 26 Nov '25

26 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42850 SUBJECT: GRB 251126A: Kilonova-Catcher optical afterglow detection DATE: 25/11/26 21:24:46 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro(a)hotmail.com> E. Broens (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 251126A detected by Swift (Caputo et al., GCN 42843) with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with a private telescope T-BRO operated by E. Broens. Our observations started at TGRB+35 min and were taken unfiltered. In our stacked frames, subtracted from the PanSTARRS DR2 template image, we marginally detect the optical counterpart reported by GIT (Swain, GCN 42844). Despite the pretty low SNR (while the source is visible by eye in our image), we performed a forced photometry at the position we found to be at RA, Dec (J2000): 99.9440, +54.9864. We report our follow-up results in the table below: +---------------+-----------+---------+----------------+-------------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | +===============+===========+=========+================+=============+ | 0.83 | 10 x 180s | r (AB) | 19.43 +/- 0.42 | T-BRO | +---------------+-----------+---------+----------------+-------------+ Compared to the magnitude reported by GIT (Swain, GCN 42844) the source has significantly faded even when considering our marginal detection which induced large error bars on the source photometry. Therefore, we confirm that this source is likely the optical afterglow of GRB 251126A. This is in agreement with the detections also reported by the Nanshan/HMT team (Fu et al., GCN 42848) and the Asiago team (Reguitti et al., GCN 42849). All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the Clear filters were calibrated using the PanSTARRS DR1 catalog using the PS1-r filter. 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/42850. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40918] GRB 251126A: Asiago i-band detection
by GCN Circulars 26 Nov '25

26 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42849 SUBJECT: GRB 251126A: Asiago i-band detection DATE: 25/11/26 21:14:37 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> A. Reguitti (INAF/OAPD), L. Tomasella (INAF/OAPD), D. B. Malesani (DAWN/NIB and Radboud), report on behalf of a larger collaboration: We observed the optical afterglow (Swain et al., GCN 42844; Fu et al., GCN 42848) of GRB 251126A (Caputo et al., GCN 42843) using the 67/92 Schmidt Telescope located at the Asiago observatory (Italy). Observations were carried out using the Sloan i filter. In a single exposure with start time 2025 Nov 26.8252 UT (37.8 min after the Swift/BAT trigger), the afterglow is detected with a magnitude i = 18.27 +- 0.15 (AB), calibrated against nearby stars fron the Pan-STARRS catalog, and not corrected for Galactic extinction. Compared to the earlier optical measurements (Swain et al., GCN 42844; Fu et al., GCN 42848), our images seem to indicate a red r-i color for the optical afterglow. View this GCN Circular online at https://gcn.nasa.gov/circulars/42849. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40917] GRB 251126A: Nanshan/HMT optical afterglow detection
by GCN Circulars 26 Nov '25

26 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42848 SUBJECT: GRB 251126A: Nanshan/HMT optical afterglow detection DATE: 25/11/26 21:01:26 GMT FROM: syfu(a)nao.cas.cn S.Y. Fu (HUST), S.Q. Jiang, J. An, X. Liu, L.B. He, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the field of GRB 251126A detected by Swift/BAT (Caputo et al., GCN 42843) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 19:11:52 UT on 2025-11-26, i.e., 76 seconds after the Swift/BAT trigger, and a series of unfiltered frames with different exposures were obtained. An uncatalogued and varying optical source is detected within the XRT error circle (Caputo et al., GCN 42843) at coordinates: R.A.(J2000) = 06:39:46.56 Dec.(J2000) = +54:59:12.27 with an uncertainty of ~0.5 arcsec. This position is consistent with the previous report by GIT (Swain, GCN 42844). The source has ~ 19.0 mag in the first image, calibrated with the nearby Pan-STARRS field and not corrected for Galactic extinction. The early light curve initially shows a slow rise, reaching a peak at ~150s, and then decays with power law index of ~0.5. Thus, we conclude that the source is the afterglow of GRB 251126A. Observations are still ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/42848. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40916] Swift GRB 251126A: Global MASTER-Net observations report
by GCN Circulars 26 Nov '25

26 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42847 SUBJECT: Swift GRB 251126A: Global MASTER-Net observations report DATE: 25/11/26 20:34:46 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 [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 251126A ( R. Caputo et al., GCN 42843) errorbox 4521 sec after notice time and 4538 sec after trigger time at 2025-11-26 20:26:15 UT, with upper limit up to 18.4 mag. The observations began at zenith distance = 31 deg. The sun altitude is -67.1 deg. The galactic latitude b = 21 deg., longitude l = 161 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3052530 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 4629 | MASTER-Kislovodsk | C | 180 | 15.7 | 4629 | MASTER-Kislovodsk | C | 180 | 18.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42847. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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