GCN Circular 28548

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

We observed the field of GRB 201001A(Fermi GBM Team, GCN 28538
Not found
 
 
; David
et al., GCN 28539
Not found
 
 
) 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 with a series of 60 sec exposures started at
2020-10-01 16:44:38UT. Since some images were heavily affected by the
moon, we stacked the images with good conditions. We did not find any
new point sources within the enhanced Swift/XRT error circle (Evans et
al., GCN 28540
Not found
 
 
) in the 60 sec exposure images and the stacked images.
We obtained the 5-sigma limits of the stacked images as follows.

T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
6.8 2020-10-01T19:06:10.46 4020 g'>19.0, Rc>19.3, Ic>18.9
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst
T-EXP: Total Exposure time

We used the 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
Not found
 
 
;
https://github.com/MNiwano/Eclaire).

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hosokawa@hp.phys.titech.ac.jp