TITLE: GCN CIRCULAR NUMBER: 30148 SUBJECT: Fermi trigger No 644793834: Global MASTER-Net observations report DATE: 21/06/07 22:50:47 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 GRB210607.89 (trigger No 644793834,08h 46m 00.00s , -48d 40m 12.0s, R=1) errorbox 4309 sec after notice time and 4336 sec after trigger time at 2021-06-07 22:36:05 UT, with upper limit up to 17.4 mag. Observations started at twilight. The observations began at zenith distance = 33 deg. The sun altitude is -12.0 deg. The galactic latitude b = -3 deg., longitude l = 268 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1630696 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 4366 | 2021-06-07 22:36:05 | MASTER-OAFA | (08h 36m 56.04s , -48d 48m 55.0s) | C | 60 | 17.1 | 4446 | 2021-06-07 22:37:25 | MASTER-OAFA | (08h 48m 50.37s , -48d 49m 38.2s) | C | 60 | 17.2 | 4526 | 2021-06-07 22:38:44 | MASTER-OAFA | (08h 33m 30.94s , -50d 42m 08.9s) | C | 60 | 17.3 | 4605 | 2021-06-07 22:40:04 | MASTER-OAFA | (08h 45m 58.52s , -50d 43m 28.4s) | C | 60 | 17.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.