TITLE: GCN CIRCULAR NUMBER: 33497 SUBJECT: Fermi GRB 230321A: Global MASTER-Net observations report DATE: 23/03/21 14:15:09 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (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 (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-Amur robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB 230321A ( Fermi GBM team, GCN 33490) errorbox 31100 sec after notice time and 31106 sec after trigger time at 2023-03-21 13:00:10 UT, with upper limit up to 17.0 mag. The observations began at zenith distance = 54 deg. The sun altitude is -29.6 deg. The galactic latitude b = -8 deg., longitude l = 175 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2205320 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 31137 | 2023-03-21 13:00:10 | MASTER-Amur | (05h 01m 25.52s , +27d 54m 19.8s) | C | 60 | 17.0 | 31219 | 2023-03-21 13:01:32 | MASTER-Amur | (05h 10m 28.51s , +27d 52m 42.3s) | C | 60 | 16.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.