[vsnet-grb-info 16560] GRB 150518A: MITSuME Akeno Optical observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17841
SUBJECT: GRB 150518A: MITSuME Akeno Optical observation
DATE:    15/05/21 17:36:01 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac at m.titech.ac.jp>

S.Harita, T.Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana, H. Ohuchi, Y. Yano,
S. Kurita, Y.Ono, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the XRT-UVOT enhanced position of GRB150518A (T.Kawamuro et al., GCN Circular #17825) 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 2015-05-19 11:08:33 UT (~13.5 h after the burst).
We detected the previously reported optical afterglow of GRB150518A (B.Sbarufatti et al., GCN Circular #17827) in the Rc and Ic band.
Although estimated magnitude of Ic band has large error, we could find a faint point source.

We obtained following limits for the magnitudes.

T0+[sec]      MID-UT      T-EXP[sec]         g'           Rc           Ic
------------------------------------------------------------------------------------------------
  48379     13:43:24          4380           >20.7      20.4+/-0.3     19.7+/-0.43
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration