TITLE: GCN CIRCULAR NUMBER: 18254 SUBJECT: GRB 150907B: MASTER-SAAO early optical observations DATE: 15/09/08 08:22:48 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs D.Buckley, S. Potter, M.Kotze South African Astronomical Observatory V. Lipunov, E.Gorbovskoy, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov, I.Gorbunov Lomonosov Moscow State University, Sternberg Astronomical Institute R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias A. Tlatov, D. Dormidontov, V.Senik Kislovodsk Solar Station of the Pulkovo Observatory K.Ivanov, O.Gres, N.M.Budnev, S.Yazev, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University 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) Carlos Lopez, Claudio Mallamaci and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was pointed to the Swift Alert (Roegiers et al., GCN 18249) GRB150907B 25 sec after notice time and 40 sec after trigger time at 2015-09-07 23:27:10 UT. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box (ra=17 00 51 dec=-63 49 07 r=0.050000). The next images limit without OT: Id Coord Pro.type Time,UT Exp.time Lim Filt. Tube 110113 16h 59m 04.1s -63d 41m 01s Alert 23:27:10 10 15.5 P EAST 110114 17h 00m 00.1s -63d 42m 55s Alert 23:27:10 10 15.7 P WEST 110115 16h 59m 47.7s -63d 42m 57s Alert 23:27:34 10 15.4 P WEST 110116 16h 59m 22.0s -63d 41m 10s Alert 23:27:34 10 15.2 P EAST 110117 16h 59m 47.5s -63d 42m 57s Alert 23:27:56 20 15.9 P WEST 110118 16h 59m 21.8s -63d 41m 10s Alert 23:27:56 20 15.7 P EAST 110119 16h 59m 21.6s -63d 41m 09s Alert 23:28:27 20 15.9 P EAST 110120 16h 59m 47.4s -63d 42m 56s Alert 23:28:27 20 16.1 P WEST 110121 16h 59m 21.6s -63d 41m 09s Alert 23:28:58 30 13.2 P EAST 110122 16h 59m 47.4s -63d 42m 56s Alert 23:28:58 30 13.5 P WEST 110123 17h 00m 00.1s -63d 42m 55s SumAlert23:27:10 40 16.3 P WEST 110124 16h 59m 21.4s -63d 41m 08s Alert 23:29:39 40 15.1 P EAST 110125 16h 59m 47.1s -63d 42m 55s Alert 23:29:39 40 15.5 P WEST 110126 16h 59m 04.1s -63d 41m 01s SumAlert23:27:10 40 16.1 P EAST 110127 16h 59m 47.1s -63d 42m 55s Alert 23:30:30 50 15.9 P WEST 110128 16h 59m 21.3s -63d 41m 08s Alert 23:30:30 50 15.5 P EAST 110129 16h 59m 47.4s -63d 42m 56s SumAlert23:28:27 90 15.9 P WEST 110130 16h 59m 21.2s -63d 41m 08s Alert 23:31:31 60 14.8 P EAST 110131 16h 59m 47.1s -63d 42m 56s Alert 23:31:31 60 15.4 P WEST 110132 16h 59m 21.6s -63d 41m 09s SumAlert23:28:27 110 16.1 P EAST There was a short time between rain and clouds. Then the clouds returned. The message may be cited.