TITLE: GCN CIRCULAR NUMBER: 16794 SUBJECT: GRB 140907A: MITSuME Ishigakijima Optical Observation DATE: 14/09/08 00:47:24 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (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 Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. The observation started on 2014-09-07 16:18:10 UT (~11 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 -------------------------------------------------------------------------- 0.01128 16:23:22 540.0 17.97 0.05 17.07 0.03 16.44 0.03 0.14407 19:34:36 540.0 19.73 0.12 19.36 0.11 18.48 0.11 -------------------------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]