TITLE: GCN CIRCULAR NUMBER: 9065 SUBJECT: GRB 090328B: MASTER-Irkutsk prompt optical short burst observations DATE: 09/04/01 08:47:35 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs K.Ivanov, S.Yazev, Irkutsk State University E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina, D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalognikh, T.Kopytova Ural State University, Kourovka There are 6 MASTER Very Wide Field cameras located at Kislovodsk and Irkutsk with common FOW = 6000 square degrees (http://observ.pereplet.ru/). One of the two MASTER Very Wide Field Cameras located at Irkutsk (D=50 mm, 2x1000 square degrees, 11 Mpx) has observed ~20% 1-sigma Fermi error box (A. Goldstein, GCN 9056) with 1s exposure during all night: befoure, during and after GRB Time without time gap between images. Our unfiltered images are calibrated relative to Tycho stars (V). The magnitude limit of the each emage is ~9.1 m at the edge of FOW (some ising was attend at this night). We do not detect OT inside 20% part of the error box. We conclude (in the case that GRB inside our FOW ): 1). the optical fluence during the short 0.3 s GRBurst is limited by ~<= 3 x 10E-9 erg/cm_2 excluding possible host galaxy absorbtion. The event fluence (8-1000 keV) in this time interval is (9.61 +/- 0.31)E-07 erg/cm^2 (A. Goldstein, GCN 9056). So: 2). Optical-Fluence/Gamma-Fluence(8-1000 keV) ~ < 1/300 The same ratio for long GRB080319B is Optical-Fluence/Gamma-Fluence(8 - 1000 keV) ~ 1/140 (Naked Eye GRB, Racusin, Karpov et al., Nature, vol.455, 183, 2008). The film of our observations is available at http://observ.pereplet.ru/images/GRB090320B/GRB090328B.gif Black circles are the 1-sigma and 3-sigma error boxes (A. Goldstein, GCN 9056). The reduction is continued. The message may be cited. mailto: lipunov@sai.msu.ru