[vsnet-grb-info 26584] GRB 201017A: MITSuME Akeno optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28684
SUBJECT: GRB 201017A: MITSuME Akeno optical upper limits
DATE:    20/10/19 14:13:28 GMT
FROM:    Ryohei Hosokawa at Tokyo Institute of Technology  <hosokawa at hp.phys.titech.ac.jp>

R. Hosokawa, K. L. Murata, R. Adachi, 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 201017A (The Fermi GBM team, GCN #28665,
A. D'Ai et al., GCN #28666, V. Lipunov et al., GCN #28667, L. P. Xin
et al., GCN #28672, S. Belkin et al., GCN #28679) 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 2020-10-17 12:53:15 UT.(186 min after
trigger) Since some images were heavily affected by bad weather, we
stacked the images with good conditions. We did not find any new point
sources within the enhanced Swift/XRT circle (M. R. Goad et al., GCN
#28671) in all three bands.
We obtained the 5-sigma limits as follows
T0+[min] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
296 17:53:37 9480 g'>20.0,Rc>19.9,Ic>19.2
------------------------------------------------------------------------------------------------
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; https://github.com/MNiwano/Eclaire).