TITLE: GCN CIRCULAR NUMBER: 26125 SUBJECT: GRB 191031D: MITSuME Akeno optical upper limits DATE: 19/11/01 10:51:07 GMT FROM: Ogawa Futa at Tokyo Institute of Technology F. Ogawa, R. Adachi, K. L. Murata, M. Oeda, K.Shiraishi, K. Iida, M. Niwano, R. Hosokawa, S. Toma, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 191031D (The Fermi GBM team, GCN Circular #26111, V. D'Elia et al., GCN Circular #26112, Bagrat Mailyan, #26114) 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 19/11/01 08:18:36 UT. We did not find any new point sources within the XRT circle (J.P. Osborne et al., GCN Circular #26117) in all three bands. We obtained the following 5-sigma limits for the magnitudes. T0+[hour]   MID-UT    T-EXP[sec]    5-sigma limits ------------------------------------------------------------------------------------------------  ~11.5         09:12:34    1680              g'>18.3, Rc>18.2, Ic>17.3 ------------------------------------------------------------------------------------------------ T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used UCAC4 catalog for flux calibration. The magnitudes are expressed in the AB system.