TITLE: GCN CIRCULAR NUMBER: 16793 SUBJECT: GRB140907A: MITSuME Okayama Optical Observation DATE: 14/09/08 00:47:19 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 140907A (Krimm et al., GCNC 16788) 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 2014-09-07 16:21:50 UT (~15 min after the burst). We detected the previously reported afterglow (Xu et al., GCNC 16789; Kuin and Krimm, GCNC 16791) in all the three bands. Photometric results of the OT are listed below. We used GSC 2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ----------------------------------------------------------------------- 0.01381 16:27:01 540.0 18.2 0.2 17.2 0.1 16.6 0.1 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]