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GCN Circular 33666

GRB 230420A: MITSuME Akeno optical observation
2023-04-21T11:43:58Z (a year ago)
Narikazu Higuchi at Tokyo Tech <>
N. Higuchi, I. Takahashi, M. Sasada, S. Sato, R. Hosokawa, M. Niwano, Y.
Yatsu (Tokyo Tech), K. L. Murata (Kyoto U) and N. Kawai (Riken) report on
behalf of the MITSuME collaboration:

We observed the field of GRB 230420A (N. J. Klingler et al. #33658, J.P.
Osborne et al. #33661,R. Strausbaugh et al. #33662, Y.-D. Hu et al.
#33663, S.Y.
Fu et al. #33664, S.Y. Fu et al. #33665) 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 2023-04-20
10:23:41 UT (280 seconds after the Swift/BAT detection). We stacked the
images with good conditions. Here we report the Rc and Ic band magnitudes
by the forced-photometry at the enhanced Swift/XRT position (J.P. Osborne
et al. GCN Circular #33661), and the 5-sigma limit of the stacked images in
the g' band.

T0+[sec] |MID-UT | T-EXP[sec] | magnitudes of forced-photometry


 588 | 2023-04-20 10:28:49| 540 | g'>18.3, Rc=18.3+/- 0.3, Ic=17.3 +/- 0.2


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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