TITLE: GCN CIRCULAR NUMBER: 42464 SUBJECT: Fermi GRB 251026B: Global MASTER-Net observations report DATE: 25/10/27 01:31:39 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-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 251026B ( Fermi GBM team, GCN 42455) errorbox 59309 sec after notice time and 62633 sec after trigger time at 2025-10-27 00:42:47 UT, with upper limit up to 18.4 mag. The observations began at zenith distance = 68 deg. The sun altitude is -32.5 deg. The galactic latitude b = 20 deg., longitude l = 239 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3023975 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 62664 | 2025-10-27 00:42:47 | MASTER-Kislovodsk | (08h 46m 04.47s , -11d 51m 14.2s) | C | 60 | 17.9 | 62664 | 2025-10-27 00:42:47 | MASTER-Kislovodsk | (08h 50m 15.56s , -12d 14m 29.7s) | C | 60 | 18.3 | 63317 | 2025-10-27 00:53:40 | MASTER-Kislovodsk | (08h 46m 04.23s , -11d 50m 49.0s) | C | 60 | 17.8 | 63317 | 2025-10-27 00:53:40 | MASTER-Kislovodsk | (08h 50m 17.20s , -12d 14m 14.5s) | C | 60 | 18.1 | 63959 | 2025-10-27 01:04:22 | MASTER-Kislovodsk | (08h 46m 02.23s , -11d 50m 25.1s) | C | 60 | 18.2 | 63959 | 2025-10-27 01:04:22 | MASTER-Kislovodsk | (08h 50m 16.29s , -12d 13m 53.6s) | C | 60 | 18.4 | 64626 | 2025-10-27 01:15:29 | MASTER-Kislovodsk | (08h 46m 09.08s , -11d 49m 58.6s) | C | 60 | 18.2 | 64626 | 2025-10-27 01:15:29 | MASTER-Kislovodsk | (08h 50m 18.58s , -12d 13m 27.0s) | C | 60 | 18.4 | 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/42464. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...