TITLE: GCN CIRCULAR NUMBER: 12374 SUBJECT: GRB 110921A: MASTER-Net early limit DATE: 11/09/21 15:00:27 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Yurkov, Yu.Sergienko, E.Sinyakov, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, S.Yazev, N.M.Budnev, E.Konstantinov, V.Lenok, O.Gres, O.Chuvalaev, V.A.Poleshchuk 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.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 MASTER II robotic telescopes (MASTER-Net: http://observ.pereplet.ru) located in Amur and in Tunka (Siberia) was pointed to the GRB110921A 7 sec after notice time and 53 sec after GRB time at 2011-09-21 13:52:13.432 UT. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box (ra=19 36 19 dec=+36 22 48 r=0.050000). Observations were made in polarizing bands. The 5-sigma upper limit has been about 17.2 in Amur and 17.5 in Tunka. Observations and data reduction is continued. The message may be cited.