TITLE: GCN CIRCULAR NUMBER: 15481 SUBJECT: GRB 131030A: MITSuME Akeno Optical observation DATE: 13/11/11 06:15:29 GMT FROM: Taketoshi Yoshii at Tokyo Tech T.Tanigawa, T. Yoshii, K. Ito, Y. Saito, Y. Yano, R. Usui, Y. Tachibana, S. Kurita, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 131030A (E. Troja et al., GCN Circular #15402) with the optical three color (g, Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2013-10-31 09:37:51 UT ( 12.68h after the burst). We detected the previously reported optical afterglow of GRB131013A (E. Troja et al., GCN Circular #15402) in the Rc and Ic band. The measured magnitudes were listed below. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------------------------------------------------------------- 43334 10:45:52 2940 >19.92 19.37+/-0.31 18.94+/-0.27 49357 12:14:44 5760 >20.72 20.05+/-0.30 19.25+/-0.24 57097 14:23:40 3780 >20.38 19.57+/-0.22 >19.51 ------------------------------------------------------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst [sec] T-EXP: Total Exposure time [sec] We used GSC2.3 catalog for flux calibration.