TITLE: GCN CIRCULAR NUMBER: 9752 SUBJECT: GRB 090807: MITSuME optical upper limit DATE: 09/08/08 07:58:00 GMT FROM: Michitoshi Yoshida at Okayama Astrophysical Obs M. Yoshida, D. Kuroda, K. Yanagisawa, Y. Shimizu, S. Nagayama, H. Toda (OAO, NAOJ) and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 090807 (Cannizzo et al. GCN 9746) with optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2009-08-07 15:03:35 UT (3m 8s after the burst). We did not find any point source in the error circle of the XRT position reported by Beardmore et al. (GCN 9748) in all the three bands. Three sigma upper limits of the OT are listed below. We used USNO B1 catalog for flux calibration. PDAY MID-UT T-EXP g' Rc Ic --------------------------------------------------- 0.00589 15:08:56 540.0 >18.3 >18.5 >18.2 0.04169 16:00:30 4860.0 >18.9 >19.1 >18.7 ---------------------------------------------------