TITLE: GCN CIRCULAR NUMBER: 12238 SUBJECT: GRB 110801A: MASTER OT observations DATE: 11/08/02 17:32:35 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs A.V. Parhomenko, A. Tlatov, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory 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.Sankovich Sternberg Astronomical Institute, Moscow State University 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 GRB110801A 101 sec after GRB time at 2011-08-01 19:51:23 UT. Unfortunatelly the objects was not in focus because recently photometer modification. On our first (20s exposure) set we haven`t found optical transient within SWIFT error-box (De Pasquale et al., GCN 12228). The 3-sigma upper limit has been about 14.0 mag (white+polarizator). MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located near Kislovodsk (Caucasus Mountains) closed roof 20 min before trigger due to cloudy condidtions. The telescope was repointed to the GRB110901A only 47 min 40 sec after trigger time at 2011-08-01 20:37:22 UT. We found OT at UVOT postion (De Pasquale et al., GCN 12228). The results of our photometry are: Time_Start T_mean-T_trig exp time m error Band UT s s 20:37:22 2950 180 16.13 0.06 R 20:44:29 3377 180 16.12 0.06 R 20:48:01 3589 180 16.29 0.08 R 20:48:01 3589 180 16.03 0.06 White 20:51:24 3792 180 16.43 0.06 R 20:51:24 3792 180 16.19 0.06 White 23:20:14 12722 180 17.75 0.10 R The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.08 in the direction of the burst (Schlegel et al. 1998). The power low index (F~t^-aplha) apha ~1.0+-0.1 during this observations in R-band. The message may be cited.