TITLE: GCN CIRCULAR NUMBER: 12053 SUBJECT: GRB110530A: MITSuME Okayama Optical Observation DATE: 11/05/31 02:34:34 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 110530A (D'Avanzo et al., GCNC 12046) 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 2011-05-30 15:41:32 UT (~11 min after the burst). We detected the previously reported afterglow (Yatsu et al., GCNC 12048) in Rc and Ic bands. Photometric results and are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Rc_err Ic Ic_err ---------------------------------------------------------------------- 0.06460 17:04:03 5520.0 >20.3 19.8 0.2 19.6 0.2 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]