TITLE: GCN CIRCULAR NUMBER: 17763 SUBJECT: GRB 150423A: MITSuME Akeno Optical observation DATE: 15/04/27 05:50:43 GMT FROM: Taketoshi Yoshii at Tokyo Tech S.Harita, T.Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana, H. Ohuchi, Y. Yano, S. Kurita, Y.Ono, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 150423A (C. Pagani et al. GCN Circular #17728) 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 2015-04-23 13:03:48 UT (~6.6 h after the burst). We did not find any new point source within XRT circle in all three bands. We obtained following limits for the magnitudes. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic --------------------------------------------------------------------------------------- 23744 16:26:45 2940 >19.4 >19.3 > 18.4 --------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration