TITLE: GCN CIRCULAR NUMBER: 28215 SUBJECT: GRB 200806A: MITSuME Akeno optical upper limits DATE: 20/08/07 05:56:59 GMT FROM: Katsuhiro L. Murata at Nagoya U K. L. Murata, R. Adachi, R. Hosokawa, M. Niwano, F. Ogawa, N. Nakamura, N. Ito, S. Ogata, H. Takamatsu, H. Hara, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration: We observed the field of GRB 200806A (Ambrosi et al., GCN 28211; Beardmore et al., GCN 28214) 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 with a series of 60 sec exposures started on 2020-08−06 15:30:34 UT. The first 15 images were heavily affected by the presence of the moon. We stacked the images excluding the 15 images and did not find any new point sources within the enhanced Swift/XRT error circle (Beardmore et al., GCN 28214) of the stacked images. We obtained the 5-sigma limits as follows. T0+[min] MID-UT T-EXP[sec] 5-sigma limits ------------------------------------------------------------------------------------------------ 19 2020-08-06T15:57:10 960 g'>16.7, Rc>16.7, Ic>16.9 ------------------------------------------------------------------------------------------------ T0+: Elapsed time after the burst T-EXP: Total Exposure time We used the PS1 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., submitted; https://github.com/MNiwano/Eclaire)