TITLE:   GCN CIRCULAR
NUMBER:  9858
SUBJECT: GRB 090831B: MITSuME optical upper limits
DATE:    09/09/01 09:35:30 GMT
FROM:    Michitoshi Yoshida at Okayama Astrophysical Obs  <yoshida@oao.nao.ac.jp>

M. Yoshida, D. Kuroda, K. Yanagisawa, Y. Shimizu, S. Nagayama,
H. Toda (OAO, NAOJ) and N. Kawai (Tokyo Tech) report on behalf
of the MITSuME collaboration:

We observed the field of GRB 090831B (De Pasquale et al. GCN
9851) with the optical three color (g', Rc and Ic) CCD camera
attached to the MITSuME 50cm telescope of Okayama Astrophysical
Observatory. The observation started on 2009-08-31 18:03:21 UT
(2m 7s after the burst). We did not find any new point source
in the BAT error circle reported by De Pasquale et al. (GCN 9851)
in all the three bands.

Three sigma upper limits of the OT are listed below. We used
GSC2.3 catalog for flux calibration.

#PDAY      MID-UT   T-EXP      g'     Rc      Ic
--------------------------------------------------
0.00505  18:09:49    540.0   >19.0   >18.8   >18.1
0.03482  18:52:41   4200.0   >19.9   >19.7   >19.0
--------------------------------------------------