TITLE: GCN CIRCULAR NUMBER: 17646 SUBJECT: GRB 150323C: MITSuME Akeno Optical observation DATE: 15/03/26 14:10:07 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 150323C (Amaral-Rogers et al. GCN Circular #17621) 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 at 2015-03-23 17:06:46 UT (85 sec after the burst). We detected the previously reported optical afterglow (Xu et al. GCN Circular #17625) in the Rc band. The measured magnitudes are listed below. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic ---------------------------------------------------------------------- 85 17:09:24 270 > 19.9 > 19.6 > 18.5 1069 17:34:06 1200 > 20.9 20.3 ± 0.5 > 19.5 6681 19:18:53 2400 > 20.4 > 20.4 > 19.4 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration.