TITLE: GCN CIRCULAR NUMBER: 15803 SUBJECT: GRB 140206A: MITSuME Akeno detection of the optical counterpart DATE: 14/02/07 04:33:05 GMT FROM: Yoichi Yatsu at Tokyo Tech. Y. Saito, T. Yoshii, Y. Tachibana, S. Kurita, K. Ito, R. Usui, K. Ishikawa, T. Tanigawa, Y. Yano, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 140206A (A. Y. Lien et al., GCNC 15784) with the optical three color (g, Rc, and Ic) CCD cameras mounted on the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2014-02-06 15:46:53 UT ( ~8.5 hour after the burst) and we detected the previously reported afterglow. The measured magnitudes were listed as follows. T0+[hour] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------ ----------------------------------------- ~8.5 17:36:31 199x60 20.74+/-0.14 18.88+/-0.08 18.37+/-0.10 ------------------------------------------------------------ ----------------------------------------- (The photon flux were calibrated by SDSS(g') and GSC2.3(Rc, Ic) catalog.)