TITLE:   GCN CIRCULAR
NUMBER:  16803
SUBJECT: GRB 140907A: MITSuME Akeno Optical Observation
DATE:    14/09/09 07:25:07 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

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

We observed the field of GRB 140907A (Krimm et al., GCN Circular #16788) 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 2014-09-07 17:05:39 UT (~1 h after the burst).
We detected the previously reported optical afterglow (Xu et al., GCN Circular #16789, Kuin and Krimm, GCN Circular #16791, Kuroda et al., GCN Circular #16793) in the g',Rc and Ic band.

The measured magnitudes are listed below.

T0+[day]  MID-UT  T-EXP[sec]    g'                Rc             Ic
------------------------------------------------------------------------------
0.04064  17:09:16  360      19.2+/-0.2  18.2+/-0.2  17.3+/-0.1
0.07348  18:07:29  300          >19.2           >18.3       >17.7
------------------------------------------------------------------------------
T0+ : Elapsed time after the burst 
T-EXP: Total Exposure time 
We used GSC2.3 catalog for flux calibration.