TITLE: GCN CIRCULAR NUMBER: 17715 SUBJECT: GRB 150413A: MITSuME Akeno Optical observation DATE: 15/04/17 13:17:03 GMT FROM: Taketoshi Yoshii at Tokyo Tech T.Fujiwara, Y. Saito, T. Yoshii, Y. Tachibana, H. Ohuchi, Y. Yano, S.Kurita, Y. Ono, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 150413A (C. B. Markwardt et al. GCN Circular #17688) 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 2015-04-13 15:58:02 UT (~2.1 h after the burst). We detected the previously reported optical afterglow (K.Ivanov et al. GCN Circular #17689) in the Ic band. The measured magnitudes are listed below. T0+ MID-UT T-EXP[sec] g' Rc Ic ---------------------------------------------------------------------- 263 min 4/13 18:17:28 240 > 17.3 > 17.2 16.09 +/- 0.30 2.04 days 4/15 14:52:50 15960 > 21.7 > 21.5 > 20.2 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration.