TITLE: GCN CIRCULAR NUMBER: 9681 SUBJECT: GRB 090715B: MASTER optical limit DATE: 09/07/16 13:32:17 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs D.Kuvshinov, V. Lipunov, V.Kornilov, E. Gorbovskoy, A.Belinski, A. Krylov, N.Shatskiy, N.Tyurina, P.Balanutsa, V.V.Chazov, P.V.Kortunov Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parkhomenko, Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalognikh, T.Kopytova, Alexander Popov Ural State University, Kourovka S.Yazev, K.Ivanov Irkutsk State University MASTER robotic telescope (MASTER-Net: http://observ.pereplet.ru, 355 mm, 6 square degrees, 16Mpx Apogee CCD) located at Vostrykovo (Moscow) responded to the GRB 090715B (Swift trigger 357512, L. Vetere , GCN 9668), producing images beginning 19 s after the GCN notice time. An automated response took the first image at 21:11:18 UT, 8m 04s after the burst, under summer Moscow sky. We have 160 images with 30 sec exposition each. These unfiltered images are calibrated relative to USNO 08.R+0.2B (Usno A2.0). Individual images have limiting magnitudes ranging from 17.8-17.0; we set the following specific limits. GRB_time start UT end UT t_exp(s) mlim Coadd? ------------------------------------------------------------------- 484 - 514s 21:11:18 21:41:18 30 17.8 no 484 - 699s 21:11:18 21:14:57 90 18.5 3 484 - 6699S 21:11:18 22:54:27 3330 20.0 111 Robot do not detect OT with limit 20.0 . The message may be cited. mailto: lipunov@sai.msu.ru