TITLE: GCN CIRCULAR NUMBER: 23617 SUBJECT: GRB 190106A: MITSuME Akeno optical observation DATE: 19/01/06 14:36:58 GMT FROM: Ryosuke Itoh at Tokyo Institute of Tech. R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita, K. Shiraishi, K. Iida, M. Niwano, R. Adachi, M. Oeda, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration We searched for the optical counterpart of GRB 190106A (Sonbas et al., GCN Circular #23615) 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 13:35:33 UT which corresponds to 49 sec after the trigger. We detected the point source at the position consistent with the Swift/UVOT observation (Sonbas et al., GCN Circular #23615) and MASTER observation (Lipunov et al., GCN Circular #23616). The measured magnitudes are listed as follows. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------------------------------- ~49 13:36:02.6 60 ~16.1 ~15.6 ~15.5 ------------------------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used UCAC-4 catalog for flux calibration. The magnitudes are expressed in the AB system. Further analysis is ongoing.