TITLE: GCN CIRCULAR NUMBER: 14513 SUBJECT: GRB 130427A: MITSuME Ishigakijima Optical Observation after 2 days DATE: 13/04/30 14:33:12 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (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 130427A (Masell et al., GCNC 14448) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. We detected the previously reported afterglow (Elenin et al., GCNC 14450) in all the three bands. The observation started on 2013-04-29 15:02:55 UT (~2.30 days after the burst). 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 ----------------------------------------------------------------------- 2.31262 15:18:06 1500.0 19.19 0.05 18.87 0.04 18.65 0.09 2.33383 15:48:38 1440.0 19.29 0.06 18.90 0.05 18.76 0.11 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]