GCN Circular 32138

Y. Imai, S. Sato, R. Hosokawa, K. L. Murata, M. Sasada, M. Niwano, N.
Ito, Y. Takamatsu, M. Tateda, T. Hattori, Y. Yatsu, and N. Kawai
(Tokyo Tech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 220527A (A. Ursi et al. GCN Circular
#32129, The Fermi GBM team et al. GCN Circular #32130, Bissaldi  et
al. GCN Circular #32131, Evans et al. GCN Circular #32132, Mangan et
al. GCN Circular #32133, Sbarufatti et al. GCN Circular #32135,
Tohuvavohu et al. GCN Circular #32136,) with the optical three color
(g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope
Akeno.

The observation with a series of 60 sec exposures started at
2022-05-27 16:05:50 UT (6.8 hours after the AGILE detection). We
stacked the images with good conditions. Here we report magnitudes by
the forced-photometry at the Swift/XRT position (Sbarufatti et al. GCN
Circular #32135).

T0+[hour] |MID-UT | T-EXP[sec] | magnitudes of forced-photometry
------------------------------------------------------------------------------------------------
7.5 | 2022-05-27 16:46:53| 3780 | g'=18.9 +/- 0.2, Rc=18.5 +/- 0.1,
Ic=18.3 +/- 0.1
8.7 | 2022-05-27 17:58:38| 3420 | g'=18.9 +/- 0.2, Rc=18.6 +/- 0.1,
Ic=18.7 +/- 0.2
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time

We used 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. 2021, PASJ, Vol.73,
Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).