TITLE: GCN CIRCULAR NUMBER: 25854 SUBJECT: GRB 190926A: MITSuME Akeno optical upper limits DATE: 19/09/27 03:33:15 GMT FROM: Adachi Ryo at Tokyo Institute of Tech R. Adachi, K. L. Murata, M. Oeda, K.Shiraishi, K. Iida, M. Niwano, F. Ogawa, 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 190926A (A. Melandri et al., GCN Circular #25848) 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 16:16:33 UT. We did not find any new point sources within the XRT circle (M.R. Goad et al., GCN Circular #25850) in all three bands. We obtained the following 5-sigma limits for the magnitudes. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits ------------------------------------------------------------------------------------------------ ~7.0 18:13:34 6960 g'>19.8, Rc>19.5, Ic>19.2 ------------------------------------------------------------------------------------------------ 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.