TITLE: GCN CIRCULAR NUMBER: 29336 SUBJECT: Fermi GRB 210120A: Global MASTER-Net observations report DATE: 21/01/20 09:00:10 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 GRB 210120A ( Fermi GBM team, GCN 29334) errorbox 80 sec after notice time and 143 sec after trigger time at 2021-01-20 07:13:07 UT, with upper limit up to 19.5 mag. The observations began at zenith distance = 50 deg. The sun altitude is -27.8 deg. The galactic latitude b = 61 deg., longitude l = 228 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1529824 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 158 | 2021-01-20 07:13:07 | MASTER-OAFA | (11h 02m 27.64s , +18d 11m 39.0s) | C | 30 | 18.3 | 214 | 2021-01-20 07:13:58 | MASTER-OAFA | (11h 02m 27.67s , +18d 10m 13.7s) | C | 40 | 18.4 | 279 | 2021-01-20 07:14:58 | MASTER-OAFA | (11h 02m 30.93s , +18d 11m 51.7s) | C | 50 | 19.0 | 353 | 2021-01-20 07:16:07 | MASTER-OAFA | (11h 02m 25.55s , +18d 10m 58.1s) | C | 60 | 18.8 | 646 | 2021-01-20 07:20:30 | MASTER-OAFA | (10h 52m 05.03s , +16d 29m 39.0s) | C | 120 | 19.2 | 795 | 2021-01-20 07:22:49 | MASTER-OAFA | (10h 52m 11.15s , +16d 29m 48.7s) | C | 140 | 19.4 | 974 | 2021-01-20 07:25:29 | MASTER-OAFA | (10h 52m 07.89s , +16d 31m 35.3s) | C | 180 | 19.5 | 1174 | 2021-01-20 07:28:48 | MASTER-OAFA | (10h 52m 07.90s , +16d 30m 04.6s) | C | 180 | 19.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.