[vsnet-grb-info 20740] GRB 180624A: MITSuME Okayama optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22838
SUBJECT: GRB 180624A: MITSuME Okayama optical upper limits
DATE:    18/06/25 04:46:32 GMT
FROM:    Ryosuke Itoh at Tokyo Institute of Tech.  <itoh at hp.phys.titech.ac.jp>

R. Itoh,  K. L. Murata, Y. Tachibana, K. Morita,
K. Shiraishi, M. Oeda, R. Adachi, K. Iida, S. Niwano,   Y. Yatsu, and
N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 180624A (S. L. Gibson et al., GCN Circular #22832)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2018-06-24 13:51:38.54 UT (~118 sec after
the burst). We did not find any new point source within the
enhanced XRT error circle in all the three bands.

We obtained following limits for the magnitudes.

T0+[sec]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
~118      ~13:52:08      60   >15.5   >16.1   >16.2
~1537    ~14:15:47   2100   >17.2   >17.7   >17.6
-------------------------------------------------------------------------------------------------------

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