GCN Circular 22001

S. Harita, R. Itoh, K. L. Muarata, Y. Tachibana, T. Yoshii, K. Morita, T.
Ozawa, H. Mamiya, K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We have been observing the optical counterpart of GRB 171010A (N. Omodei et
al., GCN Circular #21985) 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 2017-10-11 13:29:52.24 UT.
We detected the previously reported optical afterglow (Thorstensen &
Halpern, GCN Circular #21987; Izzo & Malesani, GCN Circular #21988;
Guidorzi et al., GCN Circular #21991; Malesani et al., GCN Circular #22000)
in Ic and Rc bands.
The measured magnitudes were listed as follows.

T0+[hour]    MID-UT      T-EXP[sec]         g'              Rc
       Ic
-------------------------------------------------------------------------------------------------------
~18.29         15:23:32          4380           >18.8    18.04+/- 0.16
 17.331 +/- 0.12
-------------------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.