GCN Circular 27813

F. Ogawa, R. Hosokawa, R. Adachi, K. L. Murata, M. Niwano, N.
Nakamura, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the
MITSuME collaboration:

We observed the field of GRB 200524A (Fermi-LAT detection: Dirirsa et
al., GCN #27797, Fermi-GBM detection: Pookalil et al., GCN #27809,
Swift-XRT afterglow detection: Capalbi et al. GCN #27811, and others)
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 13:07:01.89 UT. We detected a point source
clearly in g' and Rc band, and marginally in Ic band at the position
consistent with the afterglow reported previously (Ho et al., GCN
#27799, Kumar et al., GCN #27800, Rumyantsev et al., GCN #27802,
Sanwal et al., GCN #27803, Perley et al., GCN #27805, Kumar et al.,
GCN #27806, de Ugarte Postigo et al., GCN #27807, Blazek et al., GCN
#27810). We measured the magnitudes as follows.

T0+[hour] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
8.03 13:10:54 420 g'=19.6+/-0.3, Rc=19.5+/-0.3, Ic=19.4+/-0.5
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst
T-EXP: Total Exposure time

We used GSC2.3 catalog for flux calibration. The magnitudes are
expressed in the Vega system. The images were processed in real-time
through the MITSuME GPU reduction pipeline (Niwano et al. ,in prep;
https://github.com/MNiwano/Eclair)