TITLE: GCN CIRCULAR NUMBER: 18765 SUBJECT: GRB 151229A: MITSuME Akeno optical upper limits DATE: 15/12/30 07:08:42 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 151229A (D. Kocevski et al., GCN Circular #18745) 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 2015-12-29 08:56:00 UT (~2.1 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 ------------------------------------------------------------------------------------------------- 7533 09:20:52 2700 > 19.5 > 19.4 > 18.6 ------------------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration.