TITLE: GCN CIRCULAR NUMBER: 19653 SUBJECT: GRB 160703A: MITSuME Ishigakijima Optical Observation DATE: 16/07/05 01:03:31 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 160703A (Cenko et al., GCNC 19645) 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 2016-07-03 12:12:55 UT, (~2.8 min after the burst). We detected the previously reported afterglow (Tachibana et al., GCNC 19652) in in all the three bands. The photometric results of the OT are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' g'_e Rc Rc_e Ic Ic_e ------------------------------------------------------------------- 0.00232 12:13:25 60.0 14.02 0.02 13.73 0.02 13.35 0.01 0.13017 15:17:31 540.0 19.32 0.07 18.37 0.04 18.22 0.08 ------------------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]