TITLE: GCN CIRCULAR NUMBER: 30328 SUBJECT: Fermi trigger No 646322348: Global MASTER-Net observations report DATE: 21/06/26 23:31:31 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB210625.58 (trigger No 646322348,07h 17m 28.08s , -14d 07m 58.8s, R=27.72) errorbox 1 days 32553 sec after notice time and 1 days 32580 sec after trigger time at 2021-06-26 23:02:03 UT, with upper limit up to 18.2 mag. Observations started at twilight. The observations began at zenith distance = 65 deg. The sun altitude is -16.7 deg. The galactic latitude b = -0 deg., longitude l = 229 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1644614 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 119070 | 2021-06-26 23:02:03 | MASTER-OAFA | (08h 32m 06.24s , -04d 43m 41.0s) | C | 180 | 18.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.