TITLE: GCN CIRCULAR NUMBER: 21070 SUBJECT: LIGO/Virgo G284239: MASTER automatic follow up and synchronous observations DATE: 17/05/05 13:31:04 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, E. Gorbovskoy, V.G.Kornilov, N.Tyurina, V.Shumkov, D.Kuvshinov, P.Balanutsa, O.Gress, A.Kuznetsov, M.I.Panchenko, A.V.Krylov, I.Gorbunov Lomonosov Moscow State University, Sternberg Astronomical Institute N.M. Budnev, O. Gress, K. Ivanov, S.Yazev Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , National University of San Juan, Argentina H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina D.Buckley, S. Potter, M. Kotze, South African Astronomical Observatory R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu The Instituto de Astrofisica de Canarias A. Tlatov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory MASTER-Kislovodsk observed part of the G284239 error field synchronousely by very wide field cameras (MASTER-VWFC 2x380 square degrees) with m_lim=11 mag on the single images and m_lim=12.5 1 minute started from trigger time. MASTER-Tunka started inspection of LIGO G284239 event (A.Weinstein et al. GCN21060) 7478 s after Notice Time on 2017-05-03 16:34:32UT. MASTER II robotic telescope located in SAAO was starting survey on the LVC GWB 170502.93 error-box 19358 sec after notice time and 77992 sec after trigger time at 2017-05-03 20:05:59 UT. MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in IAC was starting survey on the LVC GWB 170502.93 error-box 26505 sec after notice time and 85139 sec after trigger time at 2017-05-03 22:05:06 UT. Covering area is the 1142 square degrees. The covering map is available at http://master.sai.msu.ru/static//ligo/db/G284239/151//img/ligo_master_2017-05-05-10-15-24.eb.180.0.png