TITLE: GCN CIRCULAR NUMBER: 18221 SUBJECT: GRB 150831B: MASTER-IAC early optical observations DATE: 15/09/01 07:28:29 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; http://161.72.133.2/) located in IAC was pointed to the GRB150831B 24 sec after notice time and 56 sec after trigger time at 2015-08-31 22:20:23 UT (Swift: Marshall et al., GCN 18215; and Fermi: Veres and C. Meegan, GCN 18220) . On our first (10s exposure) set (two polarisations) we did not found optical transient within SWIFT error-box (Marshall et al., GCN 18215; Evans et al., GCN 18217) brighter then 16.3. The observations were stoped by beautifull Canarian sun rise ( see http://observ.pereplet.ru/images/webcam01spt2015.jpg ) at 2015-09-01 06:37:36 UT. Pro.type Date time + - Exp.time Limit Filt. Tube. Start Alert 2015-08-31 22:20:23 10 16.3 P WEST Alert 2015-08-31 22:20:23 10 15.6 P EAST Alert 2015-08-31 22:21:07 20 16.4 P WEST Alert 2015-08-31 22:21:07 20 15.9 P EAST Alert 2015-08-31 22:21:37 30 16.8 P WEST Alert 2015-08-31 22:21:37 30 16.2 P EAST Alert 2015-08-31 22:22:18 30 0.0* P WEST Alert 2015-08-31 22:22:18 30 16.2 P EAST Alert 2015-08-31 22:22:57 40 16.9 P WEST Alert 2015-08-31 22:22:57 40 16.3 P EAST Alert 2015-08-31 22:23:47 50 17.0 P WEST Alert 2015-08-31 22:23:47 50 16.5 P EAST Alert 2015-08-31 22:24:47 60 17.0 P WEST Alert 2015-08-31 22:24:47 60 16.5 P EAST Alert 2015-08-31 22:25:56 80 17.2 P WEST Alert 2015-08-31 22:25:56 80 16.6 P EAST Alert 2015-08-31 22:27:26 100 17.2 P WEST Alert 2015-08-31 22:27:26 100 16.6 P EAST Alert 2015-08-31 22:29:17 120 17.3 P WEST Alert 2015-08-31 22:29:17 120 16.6 P EAST Alert 2015-08-31 22:31:27 140 17.3 P WEST Alert 2015-08-31 22:31:27 140 16.7 P EAST Alert 2015-08-31 22:33:57 170 17.3 P WEST Alert 2015-08-31 22:33:57 170 16.7 P EAST * - no stars Our server hase a lot of job in Milky Way star dust now. This message may be cited.