TITLE: GCN CIRCULAR NUMBER: 19495 SUBJECT: GRB 160601A: MITSuME Akeno optical upper limits DATE: 16/06/03 06:44:27 GMT FROM: Taketoshi Yoshii at Tokyo Tech Y. Saito, Y. Tachibana, T. Yoshii, T. Fujiwara, Y. Ono, Y. Muraki, S. Harita, T, Ozawa, K. Saisho, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 160601A (D. Kocevski et al., GCN Circular #19478) with theoptical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2016-06-01 23:43:35 UT (33 sec 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+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------------------ 0.078 16:35:35 12060 >21.7 >21.1 >19.9 ------------------------------------------------------------------------------------------ T0+ : Elapsed time after the burst. T-EXP: Total Exposure time. We used GSC2.3 catalog for flux calibration.