GCN Circular 17841

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
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  48379     13:43:24          4380           >20.7      20.4+/-0.3     19.7+/-0.43
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T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration