TITLE: GCN CIRCULAR NUMBER: 14734 SUBJECT: GRB 130603A: MITSuME Okayama Optical Observation DATE: 13/06/03 14:05:22 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 130603A (Melandri et al., GCNC 14731) 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 2013-06-03 11:14:06 UT (~5.2 h after the burst). We detected the previously reported afterglow (Melandri, GCNC 14732) 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 ----------------------------------------------------------------------- 0.22890 11:29:09 1560.0 18.3 0.3 18.4 0.2 18.1 0.3 0.24993 11:59:26 1500.0 18.9 0.3 18.8 0.2 18.2 0.3 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]