TITLE: GCN CIRCULAR NUMBER: 11314 SUBJECT: GRB 100925A / MAXI J1659-152: MASTER optical observations DATE: 10/09/29 16:00:26 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V.Kornilov, V. Lipunov, A.Belinski, N.Shatskiy, N.Tyurina, P.Balanutsa, V.V.Chazov, D.Kuvshinov, , A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Sankovich Sternberg Astronomical Institute, Moscow State University K.Ivanov, O.Chuvalaev, V.Poleschuk, E.Konstantinov, V.Lenok, O.Gres, S.Yazev, N.M.Budnev, Irkutsk State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka We observed GRB 100925A / MAXI J1659-152 (Mangano et al., GCN 11296; Barthelmy et al., GCN 11300; Marshall et al. GCN 11298; Negoro et al.ATEL 2873) in automatic regime after sunset at Tunka and Kislovodsk (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, pp. 1-7). The elevation of the source was about 15 degrees at Tunka and about 22 degrees at Kislovodsk. The results of the R photometry are: Date JD T-T_trigger [day] R[mag] [+-] Site 2010-09-25 12:09:27 2455465.00657 0.098 16.08 0.25 Tunka 2010-09-26 02:54:12 2455465.62098 0.274 16.14 0.20 Tunka 2010-09-26 16:25:36 2455466.18445 1.276 16.20 0.10 Kislo This photometry calibrated by USNOB1 stars. The message may be cited. mailto: lipunov@sai.msu.ru