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GCN Circular 31418

Subject
GRB 220107B: MITSuME Akeno optical upper limits
Date
2022-01-09T09:54:23Z (2 years ago)
From
Masafumi Niwano at Tokyo Institute of Tech <niwano@hp.phys.titech.ac.jp>
M. Niwano, R. Hosokawa, Y. Imai, K. L. Murata, Y. Takamatsu, N. Ito, R. 
Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai 
(TokyoTech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 220107B (M. Arimoto et al. GCN Circular 
#31409, P. A. Evans et al. #31407, J. D. Gropp et al. #31411,�� A. Suresh 
et al. #31412, P. Veres and C. Meegan #31414, S.Q. Jiang et al. #31417) 
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 2022-01-08 17:04:13 UT (22 hours after Fermi 
trigger). We stacked the images with good conditions. We did not detect 
any uncatalogued sources within the XRT error region (J. D. Gropp et al. 
GCN Circular #31411). We obtained the 5-sigma limits of the stacked 
images as follows.

T0+[hours] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------ 

22.0 2022-01-08 18:58:13 11820 g'>20.7, Rc>20.9, Ic>20.1
------------------------------------------------------------------------------------------------ 

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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