[vsnet-grb-info 21491] GRB 181228A: MITSuME Akeno optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23590
SUBJECT: GRB 181228A: MITSuME Akeno optical upper limits
DATE:    18/12/30 12:22:33 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata at u.phys.nagoya-u.ac.jp>

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

We searched for the optical counterpart of GRB 181228A (M. J. Moss  et al.,
GCN Circular #23570) 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 on 09:04:35.19 UT. We did not find any new point
source within the enhanced XRT circle (A.P. Beardmore et al., GCN Circular
#23574) in all three bands. We obtained following limits for the magnitudes.

T0+[hour]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
6.188       13:04:51          25320      >19.1     >19.0     >18.6
-------------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used UCAC-4 catalog for flux calibration.