TITLE: GCN CIRCULAR NUMBER: 18747 SUBJECT: GRB 151228A: MITSuME Akeno optical upper limits DATE: 15/12/29 09:15:22 GMT FROM: Taketoshi Yoshii at Tokyo Tech Y.Saito, T.Fujiwara, T. Yoshii, Y. Tano, Y. Tachibana, Y.Ono, S.Harita, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 151228A (T. N. Ukwatta et al., GCN Circular #18731) 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 2015-12-28 19:25:49 UT (~16.3 h after the burst). We did not find any new point source within BAT circle in all three bands. We obtained following limits for the magnitudes. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic -------------------------------------------------------------------------------------- 58837 20:04:32 4200 > 20.0 > 20.0 > 19.3 --------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration.