TITLE: GCN CIRCULAR NUMBER: 16259 SUBJECT: GRB 140508A: MITSuME Akeno Optical observation DATE: 14/05/13 13:52:06 GMT FROM: Taketoshi Yoshii at Tokyo Tech T. Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana, H. Ohuchi, S. Kurita, Y.Ono , Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 140508A (H.Yu et al., GCN Circular #16224) 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 2014-05-09 11:07:31 UT (32.1h after the burst). We detected the optical afterglow of GRB140508A in the g',Rc and Ic band. The measured magnitudes were listed below. T0+[h] T-EXP[sec] g' Rc Ic ---------------------------------------------------------------------------------------- 35.3 19800 20.16+/-0.22 19.74+/-0.24 18.85+/-0.17 ---------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration.