TITLE: GCN CIRCULAR NUMBER: 22399 SUBJECT: GRB 180204A: MITSuME Okayama optical upper limits DATE: 18/02/07 08:04:10 GMT FROM: Kotaro Morita at Tokyo Tech K. Morita, R. Itoh, K. L. Murata, T. Yoshii, Y. Tachibana, S. Harita, 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 180204A (K. L. Page et al., GCN Circular #22375) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Okayama Astrophysical Observatory, Japan. The observation started on 2018-02-04 9:37:11.83 UT. We did not find any new point source within the XRT circle (J. P. Osborne et al., GCN Circular #22377) in all three bands. We obtained following limits for the magnitudes. T0+[h] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------ ------------------------------------------- ~7.0 9:48:54 1140 >17.5 >17.4 >17.0 ------------------------------------------------------------ ------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration