TITLE: GCN CIRCULAR NUMBER: 16160 SUBJECT: GRB 140423A: MITSuME Okayama Optical Observation DATE: 14/04/24 04:30:15 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME and OISTER collaboration: We observed the field of GRB 140423A (Sonbas et al., GCNC 16142) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2014-04-23 10:43:36 UT (~2.2 h after the burst). We detected the previously reported afterglow (Elenin et al., GCNC 16143; Kaur et al., GCNC 16144; Ferrante et al., GCNC 16145) in all the three bands. Photometric results of the OT are listed below. We used SDSS catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ----------------------------------------------------------------------- 0.21728 13:44:45 5880.0 20.1 0.3 20.1 0.2 19.5 0.3 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]