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GCN Circular 31765

Subject
GRB 220310A: MITSuME Akeno optical observation
Date
2022-03-18T00:15:23Z (2 years ago)
From
Ryohei Hosokawa at Tokyo Institute of Technology <hosokawa@hp.phys.titech.ac.jp>
R. Hosokawa, Y. Imai, K. L. Murata, M. Niwano, N. Ito, Y. Takamatsu,
R. Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai
(Tokyo Tech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 220310A (H. Negoro et al. GCN Circular
#31725, A. Yoshida et al. GCN Circular #31730, P. A. Evans et al. GCN
Circular #31731, V. Lipunov et al. GCN Circular #31732, H. Kumar et
al. GCN Circular #31738, D. Svinkin et al. GCN Circular #31748, Ahmed
M. Fouad et al. GCN Circular #31750, S. Belkin et al. GCN Circular
#31751, A.S. Kozyrev et al. GCN Circular #31756) 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 2022-03-10 15:13:33 UT (14.7 hours after MAXI trigger). We
stacked the images with good conditions. We marginally detected the
optical counterpart candidate at the position reported previously (V.
Lipunov et al. GCN Circular #31732, H. Kumar et al. GCN Circular
#31738, Ahmed M. Fouad et al. GCN Circular #31750).
The magnitudes of the source are as follows.

T0+[hour] | Band | MID-UT | T-EXP[sec] | candidate magnitude
------------------------------------------------------------
16.1 | g' |2022-03-10 16:32:13 | 6720.0 | 19.62+/-0.18
16.1 | Rc |2022-03-10 16:32:13 | 6780.0 | 19.67+/-0.18
16.1 | Ic |2022-03-10 16:32:13 | 6780.0 | 19.05+/-0.23
------------------------------------------------------------
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).
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