TITLE: GCN CIRCULAR NUMBER: 27666 SUBJECT: Integral GRB200428.61: Global MASTER-Net observations report DATE: 20/04/28 15:19:11 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), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), 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-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the Integral GRB200428.61 (trigger No 8611,19h 34m 58.38s , +21d 53m 53.7s, R=0.0458333) errorbox 357 sec after notice time and 365 sec after trigger time at 2020-04-28 14:40:28 UT, with upper limit up to 14.7 mag. The observations began at zenith distance = 87 deg. The sun altitude is -17.5 deg. The galactic latitude b = 0 deg., longitude l = 58 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1345998 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 400 | MASTER-Tunka | P| | 70 | 12.5 | 500 | MASTER-Tunka | P| | 90 | 12.6 | 620 | MASTER-Tunka | P| | 110 | 12.3 | 1333 | MASTER-Tunka | P| | 180 | 12.9 | 1533 | MASTER-Tunka | P| | 180 | 13.0 | 1732 | MASTER-Tunka | P| | 180 | 14.1 | 1932 | MASTER-Tunka | P| | 180 | 14.4 | 2132 | MASTER-Tunka | P| | 180 | 14.5 | 2332 | MASTER-Tunka | P| | 180 | 14.7 | The observation and reduction will continue. The message may be cited.