GCN Circular 31493
Subject
GRB 220118A: MITSuME Akeno optical observation
Event
Date
2022-01-18T23:03:56Z (4 years ago)
From
Ryohei Hosokawa at Tokyo Institute of Technology <hosokawa@hp.phys.titech.ac.jp>
R. Hosokawa, N. Ito, 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 220118A(The Fermi GBM team GCN Circular
#31489, N. J. Klingler et al. GCN Circular #31490) with the optical
three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm
telescope Akeno. The observation started at 2022-01-18 18:21:29 UT (51
sec after Swift BAT trigger). We stacked the images with good
conditions. We detected the optical afterglow candidate reported by
the Swift UVOT observation (N. J. Klingler et al. GCN Circular
#31490).
The magnitudes and the 5-sigma limits of the stacked images are as follows.
T0+[sec] MID-UT T-EXP[sec] magnitude(or 5-sigma limits) 5-sigma limits
-----------------------------------------------------------------------------------------------------------------
56 | 2022-01-18 18:21:34 | 10 |g'>15.9, Rc>16.8,
Ic>16.8 | g'>15.9, Rc>16.8, Ic>16.8 |
84 | 2022-01-18 18:22:02 | 40 |g'=18.36+/-0.70, Rc=18.57+/-0.78,
Ic>17.5 | g'>17.3, Rc>17.9, Ic>17.5 |
171 | 2022-01-18 18:23:29 | 50 |g'=17.45+/-0.20, Rc=16.90+/-0.15,
Ic=17.12+/-0.41| g'>17.5, Rc>18.1, Ic>17.5 |
256 | 2022-01-18 18:24:54 | 60 |g'=17.31+/-0.18, Rc=16.87+/-0.09,
Ic=16.64+/-0.11| g'>17.7, Rc>18.5, Ic>18.1 |
325 | 2022-01-18 18:26:03 | 60 |g'=17.31+/-0.22, Rc=17.31+/-0.13,
Ic=17.08+/-0.15| g'>17.7, Rc>18.4, Ic>18.1 |
535 | 2022-01-18 18:29:33 | 300 |g'=18.21+/-0.17, Rc=17.80+/-0.10,
Ic=17.47+/-0.10| g'>18.7, Rc>19.5, Ic>19.1 |
1471 | 2022-01-18 18:45:09 | 1020 |g'=19.82+/-0.33, Rc=19.26+/-0.14,
Ic=18.81+/-0.15| g'>19.5, Rc>20.3, Ic>19.9 |
-----------------------------------------------------------------------------------------------------------------
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).