TITLE: GCN CIRCULAR NUMBER: 18286 SUBJECT: GRB 150911A: MITSuME Okayama upper limits DATE: 15/09/12 00:15:46 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 MITSuME and OISTER collaboration: We observed the field of GRB 150911A (Starling et al., GCNC 18280) 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 2015-09-11 18:41:02 UT (~41 sec after the burst). We did not find any new point source within the enhanced XRT circle (Goad et al., GCNC 18283) 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 ----------------------------------------------------- 0.01168 18:57:10 1380.0 >20.2 >19.5 >19.1 ----------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]