TITLE: GCN CIRCULAR NUMBER: 15778 SUBJECT: GRB 140102A: MITSuME Akeno Optical observation DATE: 14/01/30 14:06:05 GMT FROM: Taketoshi Yoshii at Tokyo Tech T. Yoshii, Y. Saito, S. Kurita, Y. Tachibana, K. Ito, R. Usui, T.Tanigawa, Y. Yano,Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 140102A (L. M. Z. Hagen et al., GCN Circular #15653) 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 2014-01-02 21:18:44 UT ( 67sec after the burst). We detected the previously reported optical afterglow of GRB140102A (D. Xu et al., GCN Circular #15655) in the Ic band. The measured magnitudes were listed below. T0+ MID-UT T-EXP mag ---------------------------------------------------- 67[sec] 21:18:59 30[sec] Rc = 14.36 ± 0.4 Ic = 13.01+/-0.17 ---------------------------------------------------- T0+ : Elapsed time after the burst [sec] T-EXP: Total Exposure time [sec] We used GSC2.3 catalog for flux calibration.