TITLE: GCN CIRCULAR NUMBER: 18300 SUBJECT: GRB 150912A: MASTER-IAC optical observations DATE: 15/09/12 22:30:37 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov, E.Popova Lomonosov Moscow State University, Sternberg Astronomical Institute K.Ivanov, O.Gres, N.M.Budnev, S.Yazev, Irkutsk State University D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnih 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 IAC was pointed to the GRB150912A 33865 sec (9.4 h) after trigger time at 2015-09-12 20:01:55 UT directly after the sunset. On our first single and coadd sets we haven`t found optical transient within IPN error-box (Mereghetti et. al GCN 18291). The 5-sigma upper limit has been about 19.2 on single (180 sec) and ~ 20.3 at coadd (10x180 sec) images. The message may be cited.