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GCN Circular 31474

GRB 220117B: MITSuME Akeno optical upper limits
2022-01-18T02:45:51Z (2 years ago)
Naohiro Ito at Tokyo Tech <>
N. Ito, R. Hosokawa, K. L. Murata, M. Niwano, Y. Imai, Y. Takamatsu, R.
Yamaguchi, R. Noto, S. Sato, M. Takaku, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 220117B (A. Melandri et al. GCN Circular
#31468, V. Lipunov et al. GCN Circular #31469) with the optical three color
(g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno.
The observation started at 2022-01-17 20:06:58 UT (1.5 minutes after Swift
trigger). We stacked the images with good conditions. We did not detect any
sources within the XRT error region (A. Melandri et al. GCN Circular
#31468). We obtained the 5-sigma limits of the stacked images as follows.

T0+[minutes] MID-UT T-EXP[sec] 5-sigma limits
2.9 2022-01-17 20:08:19 80 g'>16.3, Rc>16.4, Ic>15.8
28.7 2022-01-17 20:34:10 2280 g'>16.5, Rc>17.0, Ic>16.5
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;
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