[vsnet-grb-info 26597] GRB 201020A: MITSuME Akeno optical observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28697
SUBJECT: GRB 201020A: MITSuME Akeno optical observation
DATE:    20/10/20 10:25:22 GMT
FROM:    Adachi Ryo at Tokyo Institute of Tech  <adachi at hp.phys.titech.ac.jp>

R. Adachi, R. Hosokawa, K. L. Murata, M. Niwano, F. Ogawa, N.
Nakamura, N. Ito, S. Ogata, H. Takamatsu, H. Hara, Y. Yatsu, and N.
Kawai (TokyoTech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 201020A (E. Ambrosi et al.,GCN Circular
#28696) with the optical three color (g', Rc, and Ic) CCD cameras
attached to the MITSuME 50 cm telescope of Akeno Observatory,
Yamanashi, Japan.
The observation started at 2020-10-20 08:31:00 UT. The first 28 images
were heavily affected by twilight at Akeno Observatory. We detected
the point source at the position consistent with the afterglow
detected previously (E. Ambrosi et al. GCN #28696).
We measured the magnitudes as follows.

T0+[min] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
196 09:15:39 1260 g'=19.4+/-0.2, Rc=18.4+/-0.1, Ic=18.4+/-0.2
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time

We used GSC2.3 and 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., accepted for publication in PASJ,
https://arxiv.org/abs/2008.11486; https://github.com/MNiwano/Eclaire).