TITLE: GCN CIRCULAR NUMBER: 11224 SUBJECT: GRB100905A: MITSuME Okayama optical upper limits DATE: 10/09/06 08:57:02 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 100905A (Marshall et al., GCN 11214) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2010-09-05 15:31:18 UT (~23 min after the burst). We did not find any new point source within the enhanced XRT error circle (Evans et al., GCNC 11219) in all the three bands. Three sigma upper limits of the OT are listed below. We used SDSS catalog for flux calibration. T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.09641 17:27:05 10380.0 >20.9 >20.6 >19.7 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]