TITLE: GCN CIRCULAR NUMBER: 18304 SUBJECT: GRB 150912A: MITSuME Ishigakijima upper limits DATE: 15/09/14 00:44:10 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 150912A (Mereghetti et al., GCNC 18291) 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 2015-09-12 12:15:39 UT (~1.6 h after the burst). We did not find any new point source within the INTEGRAL-IBAS error circle (Mereghetti et al., GCNC 18291) in all the three bands. Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Ic ----------------------------------------------------- 0.07014 12:18:30 300.0 >19.7 >19.4 >18.6 ----------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]