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GCN Circular 22760

Subject
GRB 180602A: MITSuME Ishigakijima optical upper limits
Date
2018-06-04T16:41:32Z (6 years ago)
From
Yutaro Tachibana at Tokyo Tech <tachibana@hp.phys.titech.ac.jp>
T. Horiuchi,  H. Hanayama, M. Honma (IAO, NAOJ),
Y. Tachibana, R. Itoh, K. L. Murata, S. Harita, K. Morita, T. Ozawa, H. Mamiya,
K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 180602A
(Cenko et al., GCN Circular #22752, Osborne et al., GCN Circular #22753, Gropp and Cenko, GCN Circular #22758)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory.

The observation started on 2018-06-02 12:38:23 UT.
We did not find any point source at the position of the XRT error
circle in all three bands. We obtained following 3-sigma upper limits: 

T0+[hour]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
~4.5      12:51:13.3  1,560   >19.4   >19.1   >18.7
-------------------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used UCAC-4 catalog for flux calibration.
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