TITLE: GCN CIRCULAR NUMBER: 16250 SUBJECT: GRB 140512A: MASTER OT decay and early light curve DATE: 14/05/12 20:44:05 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, D.Denisenko, A.Sankovich Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinsky, I.Zalozhnih, A. Popov Ural Federal University, Yekaterinburg, Kourovka Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka was pointed to the GRB140512A 171 sec after trigger time at 2014-05-12 19:34:40.212 UT in two polarizations. We definetly see OT (Pagani et. al. GCN 16249) on our images in bosh polarizations. The preliminary automatic light curve available at Tab.1 and here: http://master.sai.msu.ru/static/GRB/GRB140512A_lc.png Table 1. GRB140512B early automatic light curve. T_start T-T_trig mag 2014-05-12 19:34:44.3 175 sec 13.5 2014-05-12 19:36:36.3 287 sec 13.9 2014-05-12 19:38:21.9 392 sec 14.5 2014-05-12 19:39:43.7 474 sec 14.8 2014-05-12 19:41:05.3 556 sec 15.1 2014-05-12 19:42:26.3 637 sec 15.2 2014-05-12 19:43:47.3 718 sec 15.5 2014-05-12 19:45:56.8 847 sec 16.2 Our unfiltered magnitude is well described by a parity 0.8R + 0.2B (USNO-B1) The power low index alpha from 175 to 847 seconds after the trigger is 1.5 +- 0.1 (F ~ t-apha). We erraticly reported (Ivanov et. al. GCN 16248) that we don't see object earlier because of the wrong identification. We are sorry for it. The message may be cited.