GCN Circular 23022
Subject
GRB 180721A: MITSuME Akeno optical upper limits
Date
2018-07-23T09:52:13Z (6 years ago)
From
Ryosuke Itoh at Tokyo Institute of Tech. <itoh@hp.phys.titech.ac.jp>
M. Oeda, R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita,
K. Shiraishi, K. Iida, R. Adachi, S. Niwano,
Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We searched for the optical counterpart of GRB 180721A
(B. Sbarufatti et al., GCN Circular #22994)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the MITSuME 50cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2018-07-21 13:44:45.05 UT.
We did not find any point source at the enhanced position of the
XRT error circle (M.R. Goad et al., GCN Circular #22997) in all three bands.
We obtained following 5-sigma upper limits for the magnitudes.
T0+[min] MID-UT T-EXP[sec] g' Rc Ic
-------------------------------------------------------------------------------------------------------
157.95 14:27:28 4,740 >16.9 >17.3 >16.9
-------------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used UCAC-4 catalog for flux calibration.