TITLE: GCN CIRCULAR NUMBER: 13753 SUBJECT: GRB120911A: MITSuME Okayama Optical upper limits DATE: 12/09/12 06:18:19 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 120911A (Cannizzo et al., GCNC 13744) 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 2012-09-11 13:46:32 UT, (~6.6 h after the burst). We did not find any new point source within the enhanced XRT circle (Beardmore et al., GCNC 13748) in all the three bands. Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.31808 14:46:35 5940.0 >20.6 >19.8 >19.2 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]