TITLE: GCN CIRCULAR NUMBER: 14062 SUBJECT: GRB 121211A: MITSuME Okayama Optical Observation DATE: 12/12/12 02:38:27 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 121211A (Mangano et al., GCNC 14057) 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 2012-12-11 16:29:09 UT (~2.7 h after the burst). We detected the previously reported afterglow (Japelj et al., GCNC 14058) in all the three bands. Photometric results and three sigma upper limit 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 ----------------------------------------------------------------------- 0.15443 17:29:25 6360.0 >20.5 20.4 0.2 19.6 0.3 0.23818 19:30:01 6360.0 20.9 0.3 21.1 0.3 20.1 0.3 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]