TITLE: GCN CIRCULAR NUMBER: 31699 SUBJECT: Swift GRB 220306B: Global MASTER-Net observations report DATE: 22/03/06 19:40:46 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) was pointed to the Swift GRB 220306B ( R. Caputo et al., GCN 31697) errorbox 3820 sec after notice time and 3846 sec after trigger time at 2022-03-06 19:19:44 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 55 deg. The sun altitude is -26.5 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 220306B errorbox 4093 sec after notice time and 4118 sec after trigger time at 2022-03-06 19:24:16 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 61 deg. The sun altitude is -44.4 deg. The galactic latitude b = 9 deg., longitude l = 121 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1903942 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 3937 | MASTER-Amur | R | 180 | 17.1 | 4136 | MASTER-Amur | R | 180 | 17.1 | 4209 | MASTER-Kislovodsk | C | 180 | 17.6 | 4209 | MASTER-Kislovodsk | C | 180 | 14.5 | 4336 | MASTER-Amur | R | 180 | 17.1 | 4409 | MASTER-Kislovodsk | C | 180 | 12.5 | 4536 | MASTER-Amur | R | 180 | 17.0 | 4534 | MASTER-Kislovodsk | C | 30 | 16.9 | 4534 | MASTER-Kislovodsk | C | 30 | 14.3 | 4584 | MASTER-Kislovodsk | C | 30 | 16.8 | 4584 | MASTER-Kislovodsk | C | 30 | 14.5 | 4709 | MASTER-Kislovodsk | C | 180 | 17.9 | 4709 | MASTER-Kislovodsk | C | 180 | 14.6 | 4735 | MASTER-Amur | R | 180 | 17.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.