[vsnet-grb-info 21113] GRB 180905A: MITSuME Akeno optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23211
SUBJECT: GRB 180905A: MITSuME Akeno optical upper limits
DATE:    18/09/06 05:53:52 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata at u.phys.nagoya-u.ac.jp>

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

We searched for the optical counterpart of GRB 180905A
(V. D'Elia et al., GCN Circular #23201)
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 2018-09-05 17:29:51.08 UT.
We did not find any point source at the enhanced position of the
XRT error circle (A.P. Beardmore et al., GCN Circular #23207) in all three
bands.
We obtained following 5-sigma upper limits for the magnitudes.

T0+[min]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
202.32     18:46:39  8,100   >18.9   >18.6   >18.4
-------------------------------------------------------------------------------------------------------

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