TITLE: GCN CIRCULAR NUMBER: 22623 SUBJECT: GRB 180410A: MITSuME Akeno optical upper limits DATE: 18/04/10 12:31:10 GMT FROM: Ryosuke Itoh at Tokyo Institute of Tech. R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita, T. Ozawa, H. Mamiya, K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 180410A (J. D. Gropp et al., GCN Circular #22620) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2018-04-10 10:02:24 UT. We did not find any point source at the position of the XRT error circle (P. A. Evans et al., GCN Circular #22622) in all three bands. We obtained following limits for the magnitudes. T0+[hour] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------------------------------- ~2.0 10:27:25 2,700 >18.8 >18.7 >18.0 ------------------------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used UCAC-4 catalog for flux calibration.