TITLE: GCN CIRCULAR NUMBER: 22757 SUBJECT: GRB 180602A: MITSuME Akeno optical upper limits DATE: 18/06/03 09:29:22 GMT FROM: Katsuhiro L. Murata at Nagoya U K. L. Murata, Y. Tachibana, R. Itoh, T. Yoshii, S. Harita, K. Morita, T. Ozawa, H. Mamiya, K. Shiraishi, K. Iida, M. Oeda, R. Adachi, S. Niwano, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We searched for the field of GRB 180602A (Cenko et al., GCN Circular #22752) 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 2018-06-02 11:12:09 UT (~3 hours after the burst). We did not find any new point source within the enhanced XRT error circle (Osborne et al., GCN Circular #22753) in all the three bands. T0+[hour] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------ ------------------------------------------- ~3.1 ~12:24 1200 >18.9 >18.3 >18.0 ------------------------------------------------------------ ------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration.