TITLE: GCN CIRCULAR NUMBER: 23649 SUBJECT: GRB190109A: MITSuME Akeno optical upper limits DATE: 19/01/09 12:34:19 GMT FROM: Motoki Oeda at Tokyo Inst. of Tech. M. Oeda, R. Adachi, K. L. Murata, R. Itoh, Y. Tachibana, S. Harita, K. Morita, K.Shiraishi, K. Iida, M. Niwano, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 190109A (M. J. Moss et al.,GCN Circular #23642) 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 08:18:30.05 UT. We did not find any new point source within the enhanced XRT circle (P.A. Evans et al., GCN Circular #23643) in all three bands. We obtained following 3 sigma limits for the magnitudes. T0+[hour] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------------------------------- 3.097 8:42:32.91 1140 >16.23 >15.42 >15.34 ------------------------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration.