TITLE:   GCN CIRCULAR
NUMBER:  32159
SUBJECT: GRB 220527A: MITSuME Akeno continued optical observation
DATE:    22/06/03 10:00:43 GMT
FROM:    Masafumi Niwano at Tokyo Institute of Tech  <niwano@hp.phys.titech.ac.jp>

M. Niwano, S. Sato, M. Tateda, N. Higuchi, T. Hattori, R. Hosokawa, K. 
L. Murata, M. Sasada, N. Ito, Y. Takamatsu, Y. Imai, 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 GCN Circular #32130, E. Bissaldi et al. GCN 
Circular #32131, P. A. Evans et al. GCN Circular #32132, J. Mangan et 
al. GCN Circular #32133, B. Sbarufatti et al. GCN Circular #32135, 
Tohuvavohu et al. GCN Circular #32136, Y. Imai et al. GCN Circular 
#32138, K. Yamaoka et al. GCN Circular #32139, R. Gopalakrishnan et al. 
GCN Circular #32140, D. Xu et al. GCN Circular #32141, S. de Wet et al. 
GCN Circular #32143, P. D'Avanzo et al. GCN Circular #32145, T. Sun et 
al. GCN Circular #32146, A. Lysenko et al. GCN Circular #32152, W. Zheng 
et al. GCN Circular #32158) 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 2022-05-28 
16:06:39 UT (1.3 days after the AGILE detection). We stacked the images 
with good conditions. The point source was presumably detected at the 
Swift/XRT position (Sbarufatti et al. GCN Circular #32135) with S/N~3 
only in the Rc-band image. Here we report the Rc-band magnitude by the 
forced-photometry at the position and 5-sigma limits.

T0+[days] | MID-UT | T-EXP[sec] | magnitudes of forced-photometry | 
5-sigma limits
------------------------------------------------------------------------------------------------
1.3 | 2022-05-28 17:39:36 | 4980 | Rc=20.5+/-0.3 | g'<18.6, Rc<19.3, Ic<18.5
------------------------------------------------------------------------------------------------
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).