[vsnet-grb-info 20662] GRB 180602A: MITSuME Ishigakijima optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22760
SUBJECT: GRB 180602A: MITSuME Ishigakijima optical upper limits
DATE:    18/06/04 16:41:32 GMT
FROM:    Yutaro Tachibana at Tokyo Tech  <tachibana at 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.