TITLE: GCN CIRCULAR NUMBER: 29639 SUBJECT: Fermi trigger No 637027080: Global MASTER-Net observations report DATE: 21/03/10 03:15:12 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-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 GRB210309.99 (trigger No 637027080,09h 33m 14.40s , -05d 52m 12.0s, R=11.36) errorbox 4731 sec after notice time and 8958 sec after trigger time at 2021-03-10 02:27:13 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 27 deg. The sun altitude is -41.8 deg. The galactic latitude b = 32 deg., longitude l = 241 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1565153 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 8989 | 2021-03-10 02:27:13 | MASTER-OAFA | (09h 33m 55.28s , -05d 11m 53.5s) | C | 60 | 19.3 | 9068 | 2021-03-10 02:28:33 | MASTER-OAFA | (09h 32m 09.85s , -03d 12m 50.7s) | C | 60 | 19.2 | 9148 | 2021-03-10 02:29:52 | MASTER-OAFA | (09h 17m 45.72s , -05d 13m 02.0s) | C | 60 | 19.2 | 9227 | 2021-03-10 02:31:12 | MASTER-OAFA | (09h 20m 08.41s , -07d 12m 14.1s) | C | 60 | 19.2 | 9306 | 2021-03-10 02:32:31 | MASTER-OAFA | (09h 36m 23.14s , -07d 11m 50.0s) | C | 60 | 19.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.