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GCN Circular 31776

GRB 220319A: MITSuME Akeno optical upper limits
2022-03-20T16:06:24Z (2 years ago)
Ryohei Hosokawa at Tokyo Institute of Technology <>
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 220319A (K. L. Page et al. GCN Circular
#31769, V.Lipunov et al. GCN Circular #31770, M.R. Goad et al. GCN
Circular #31771, J. D. Gropp et al. GCN Circular #31772, S. Belkin et
al. GCN Circular #31773, R. Strausbaugh et al. GCN Circular #31774, A.
de Ugarte Postigo et al. GCN Circular #31775) 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 10 sec exposures
started at 2022-03-19 17:41:30 UT (56.7 seconds after Swift BAT
trigger). We stacked the images with good conditions. We did not
detect any sources within the XRT error region (M.R. Goad et al. GCN
Circular #31771). We obtained the 5-sigma limits of the stacked images
as follows.

T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits
101  | 2022-03-19 17:42:14 | 50   | g'>17.0, Rc>16.8, Ic>16.5
762  | 2022-03-19 17:53:16 | 560  | g'>18.5, Rc>18.3, Ic>17.9
4925 | 2022-03-19 19:02:38 | 5520 | g'>19.8, Rc>19.9, Ic>19.6
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
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