TITLE: GCN CIRCULAR NUMBER: 15932 SUBJECT: GRB 140304A: MASTER OT light curve DATE: 14/03/05 18:41:37 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, M. Pruzhinskaya, D.Denisenko, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute 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.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, 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 GRB140304A (Evans et. al GCN 15915) 26 sec after notice time and 77 sec after trigger time at 2014-03-04 13:23:49 UT. We detect OT (Gorbovskoy et. al GCN 15914) in two polarization bands during ~1 h while the source was brighter than our upper limit. The preliminary photometry result available in table 1 and here http://master.sai.msu.ru/static/GRB/grb140304A.png . Table 1. Preliminary early GRB140304A observations. T_start(JD) T_trig-T_mid Exptime Mag1 Mag2 Coadd 2456721.05834 82 10 16.8 16.2 - 2456721.05931 172 30 17.2 16.9 - 2456721.06073 294 50 18.0 17.6 - 2456721.06142 358 120 18.1 17.6 2 2456721.06211 413 70 18.3 18.0 - 2456721.06724 894 580 18.5 18.5 4 2456721.08121 2070 1080 19.6 19.0 6 2456721.09812 3526 1080 19.9 19.4 6 Mag1 and Mag2 - Magnitude in two perpendicular polarizations. The power low index alpha is 0.77+-0.05 (F ~ t-apha). MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB140304A 5 sec after notice time and 46 sec after trigger time at 2014-03-04 13:23:17 UT. The observations on this site made on bad weather conditions and on high zenith distance. The 5-sigma upper limit On our first (10s exposure) image has been about 13.0 mag. The message may be cited.