TITLE: GCN CIRCULAR NUMBER: 42837 SUBJECT: Fermi GRB 251125B: Global MASTER-Net observations report DATE: 25/11/25 20:45:36 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@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-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 251125B ( Fermi GBM team, GCN 42836) errorbox 37 sec after notice time and 71 sec after trigger time at 2025-11-25 20:24:57 UT, with upper limit up to 19.8 mag. The observations began at zenith distance = 62 deg. The sun altitude is -39.2 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 251125B errorbox 40 sec after notice time and 74 sec after trigger time at 2025-11-25 20:25:00 UT, with upper limit up to 13.2 mag. The observations began at zenith distance = 79 deg. The sun altitude is -66.8 deg. The galactic latitude b = 46 deg., longitude l = 89 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3051835 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 76 | 2025-11-25 20:24:57 | MASTER-Tunka | (15h 49m 53.68s , +58d 02m 46.1s) | C | 10 | 19.0 | 77 | 2025-11-25 20:24:57 | MASTER- | (15h 50m 33.82s , +57d 56m 14.3s) | C | 10 | 18.9 | 80 | 2025-11-25 20:25:00 | MASTER-Kislovodsk | (15h 48m 55.38s , +57d 57m 14.7s) | C | 10 | 12.3 | 81 | 2025-11-25 20:25:01 | MASTER-Kislovodsk | (15h 41m 25.24s , +58d 17m 41.9s) | C | 10 | 12.3 | 613 | 2025-11-25 20:33:29 | MASTER-Tunka | (15h 50m 14.31s , +57d 20m 48.8s) | C | 60 | 19.0 | 673 | 2025-11-25 20:33:29 | MASTER-Tunka | (15h 50m 14.31s , +57d 20m 48.8s) | C | 180 | 19.8 | Coadd 613 | 2025-11-25 20:33:29 | MASTER- | (15h 50m 55.15s , +57d 14m 04.0s) | C | 60 | 18.9 | 649 | 2025-11-25 20:33:35 | MASTER-Kislovodsk | (15h 49m 05.73s , +57d 13m 41.7s) | C | 120 | 12.9 | 677 | 2025-11-25 20:34:32 | MASTER-Tunka | (15h 50m 14.11s , +57d 20m 48.0s) | C | 60 | 19.2 | 677 | 2025-11-25 20:34:32 | MASTER- | (15h 50m 55.07s , +57d 14m 02.7s) | C | 60 | 19.1 | 740 | 2025-11-25 20:35:36 | MASTER-Tunka | (15h 50m 13.87s , +57d 20m 46.9s) | C | 60 | 18.9 | 740 | 2025-11-25 20:35:36 | MASTER- | (15h 50m 54.92s , +57d 14m 02.1s) | C | 60 | 18.7 | 789 | 2025-11-25 20:35:54 | MASTER-Kislovodsk | (15h 49m 06.58s , +57d 13m 30.8s) | C | 120 | 13.2 | 803 | 2025-11-25 20:36:39 | MASTER-Tunka | (15h 50m 13.66s , +57d 20m 45.9s) | C | 60 | 19.5 | 804 | 2025-11-25 20:36:39 | MASTER- | (15h 50m 54.78s , +57d 14m 01.8s) | C | 60 | 19.3 | 928 | 2025-11-25 20:38:14 | MASTER-Kislovodsk | (15h 49m 07.46s , +57d 13m 23.9s) | C | 120 | 13.1 | 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/42837. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...