TITLE: GCN CIRCULAR NUMBER: 29406 SUBJECT: GRB 210205A: MITSuME Ishigaki optical observation DATE: 21/02/05 22:01:18 GMT FROM: Takashi Horiuchi at Ishigakijima Astronomical Obs Takashi Horiuchi, Hidekazu Hanayama (NAOJ), Katsuhiro L. Murata, Yoichi Yatsu, Nobuyuki Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 210205A (Dichiara et al., GCN 29397) with the optical three color (g', Rc, and Ic) CCD cameras attached to the 105 cm Murikabushi telescope of Ishigakijima Astronomical Observatory, Okinawa, Japan. The observation with a series of 60 sec exposures started on 2021-02−05 11:22:29 UT (2 min after Swift BAT trigger). We stacked the 25 images and did not find any new point sources other than the USNO-B1.0 sources from the stacked images. We obtained the SN = 10 limits as follows. T0+[min] MID-UT T-EXP[sec] SN=10 limits ------------------------------------------------------------------------------------------------ 2 2021-02-05T11:36:37 1500 g' > 18.7, Rc > 19.0, Ic > 17.8 ------------------------------------------------------------------------------------------------