TITLE: GCN CIRCULAR NUMBER: 14269 SUBJECT: GRB 130306A: MASTER-Net pre-Swift alert observation DATE: 13/03/07 15:05:43 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Denisenko, D.Kuvshinov, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, A.Sankovich Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Kislovodsk was pointed to the GRB130306A 59 sec after Fermi trigger num 384306448 at 2013-03-06 23:48:24.313 UT, i.e. 157 sec before Swift trigger time (Siegel et. al. GCN14266). The observations started on very high zenith distance about 85 deg. SWIFT error box (Siegel et. al. GCN14266) got on the edge of our FOV. On our first (10s exposure) set we haven't found optical transient within SWIFT error box. The 5-sigma upper limit has been about 13 mag. Next time we pointed to BAT position at 2013-03-06 23:52:44.60 UT by SWIFT alert. On our first (20s exposure) set we haven't found optical transient within SWIFT error-box with upper limit 15.2m. On coadd image of 8 sets with total exposure 420 sec upper limit is 17.0m (5-sigma). Galactic extinction in the direction of GRB 130306 is A_R=3.7, A_I=2.7 (from to Schlegel et al., 1998) and A_R=3.0, A_I=2.1 (according to Schlafly et al., 2011). The message may be cited.