TITLE: GCN CIRCULAR NUMBER: 12289 SUBJECT: GRB 110820A: MASTER-NET observations DATE: 11/08/20 18:05:47 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev,E.Konstantinov, Irkutsk State University E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Sankovich Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka(Siberia) was pointed to the GRB110820A 45 sec after notice time and 133 sec after GRB time at 2011-08-20 17:40:40.275 UT in two polarizations. On our first (30s exposure) set we haven`t found optical transient within SWIFT error-box. The 5-sigma upper limit has been about 16.5 mag The message may be cited.