TITLE: GCN CIRCULAR NUMBER: 29649 SUBJECT: Integral GRB210312.87: Global MASTER-Net observations report DATE: 21/03/12 20:57:08 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Integral GRB210312.87 (trigger No 9073,10h 23m 22.09s , +76d 52m 36.7s, R=0.0491667) errorbox 27 sec after notice time and 41 sec after trigger time at 2021-03-12 20:52:58 UT, with upper limit up to 15.9 mag. The observations began at zenith distance = 34 deg. The sun altitude is -49.6 deg. The galactic latitude b = 38 deg., longitude l = 133 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1567228 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 46 | MASTER-Kislovodsk | P- | 10 | 14.9 | 46 | MASTER-Kislovodsk | P| | 10 | 15.8 | 64 | MASTER-Kislovodsk | P- | 10 | 14.9 | 64 | MASTER-Kislovodsk | P| | 10 | 15.9 | The observation and reduction will continue. The message may be cited.