TITLE: GCN CIRCULAR NUMBER: 13846 SUBJECT: GRB 121011A: MITSuME Okayama Optical Observation DATE: 12/10/11 12:11:41 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 121011A (Racusin et al., GCNC 13845) 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 2012-10-11 11:17:00 UT, (~90 sec after the burst) We detected the previously reported afterglow (Racusin et al., GCNC 13845) in all the three bands. Photometric results of the OT are listed below. We used SDSS catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ----------------------------------------------------------------------- 0.00449 11:21:58 540.0 17.23 0.09 16.81 0.05 16.11 0.05 0.01159 11:32:11 540.0 17.36 0.10 16.65 0.04 16.10 0.04 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]