TITLE: GCN CIRCULAR NUMBER: 28269 SUBJECT: GRB 200819A: MITSuME Akeno optical upper limits DATE: 20/08/19 23:59:46 GMT FROM: Katsuhiro L. Murata at Nagoya U K. L. Murata, R. Hosokawa, R. Adachi, M. Niwano, F. Ogawa, N. Nakamura, N. Ito, S. Ogata, H. Takamatsu, H. Hara, Y. Yatsu, and N. Kawai (Tokyo Tech), Takashi Horiuchi, Hidekazu Hanayama (NAOJ) report on behalf of the MITSuME collaboration: We observed the field of GRB 200819A (Dichiara et al., GCN 28263; Evans et al., GCN 28265) with the optical three color (gā€™, 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 2020-08āˆ’19 15:45:44 UT. Some images were heavily affected by bad weather conditions. We stacked the images with good weather conditions. We did not find any new point sources within the enhanced Swift/XRT error circle (Evans et al., GCN 28265) of the stacked images. We obtained the 5-sigma limits as follows. T0+[sec] MID-UT T-EXP[sec] 5-sigma limits ------------------------------------------------------------------------------------------------ ~290 2020-08-19T17:36:48 5640 gā€™>18.4, Rc>19.0, Ic>19.3 ------------------------------------------------------------------------------------------------ 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)