TITLE: GCN CIRCULAR NUMBER: 18630 SUBJECT: GRB 151118A: MITSuME Akeno optical upper limits DATE: 15/11/21 08:27:02 GMT FROM: Taketoshi Yoshii at Tokyo Tech Y.Yano, T.Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana, Y.Ono, S.Harita, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 151118A (A. Amaral–Rogers et al., GCN Circular #18611) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2015-11-18 19:14:09 UT (~16.1 h after the burst). We did not find any new point source within XRT circle in all three bands. We obtained following limits for the magnitudes. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------- 58059 19:44:17 2520 > 20.3 > 19.6 > 18.4 ------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration.