TITLE: GCN CIRCULAR NUMBER: 27236 SUBJECT: GRB 200227A: MITSuME Akeno optical upper limit DATE: 20/02/27 11:59:48 GMT FROM: Motoki Oeda at Tokyo Inst. of Tech. M. Oeda, R. Adachi, K. L. Murata, K. Shiraishi, K. Iida, M. Niwano, F. Ogawa, S. Toma, R. Hosokawa, N. Nakamura, Y. Yatsu, and N. Kawai(TokyoTech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 200227A (Fermi GBM Team et al.,GCN Circular #27233, S. Laha et al., GCN Circular #27234) 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 09:05:08 UT. We did not find any new point sources within the Swift/XRT circle (S. Laha et al., GCN Circular #27234) in all three bands. We obtained the 5-sigma limits as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits ------------------------------------------------------------------------------------------------ 2.2 09:41:13 900 g’>18.4,Rc>18.2,Ic>17.5 ------------------------------------------------------------------------------------------------ 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. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. ,in prep; https://github.com/MNiwano/Eclair)