TITLE: GCN CIRCULAR NUMBER: 12743 SUBJECT: GRB111228A: MITSuME Okayama Optical Observation DATE: 11/12/28 21:50:56 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 111225A (Ukwatta et al., GCNC 12737) 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 2011-12-28 15:47:03 UT (~2.3 min after the burst). We detected the previously reported afterglow (Ukwatta, GCNC 12737; Xin et al., GCNC 12738) in all the three bands. Photometric results and 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 ---------------------------------------------------------------------- 0.00511 15:52:04 540.0 17.45 0.06 17.13 0.05 16.52 0.05 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]