TITLE: GCN CIRCULAR NUMBER: 28498 SUBJECT: Swift GRB200925.91: Global MASTER-Net observations report DATE: 20/09/25 21:56:12 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB200925.91 (trigger No 997453,16h 27m 24.24s , +78d 23m 38.4s, R=0.05) errorbox 14 sec after notice time and 58 sec after trigger time at 2020-09-25 21:51:35 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 53 deg. The sun altitude is -47.0 deg. The galactic latitude b = 34 deg., longitude l = 112 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1449109 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 64 | MASTER-Tavrida | C | 10 | 17.1 | 99 | MASTER-Tavrida | C | 20 | 17.9 | 139 | MASTER-Tavrida | C | 20 | 17.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.