[vsnet-grb-info 5446] GRB071118 MITSuME OAO optical observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7119
SUBJECT: GRB071118 MITSuME OAO optical observation
DATE:    07/11/20 02:43:54 GMT
FROM:    Michitoshi Yoshida at Okayama Astrophysical Obs  <yoshida at oao.nao.ac.jp>

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

We performed optical imaging observations (g', Rc and Ic) of the field
of GRB 071118 (Cummings et al., GCN 7106; Markwardt et al. GCN 7109)
with 50cm MITSuME telescope at Okayama Astrophysical Observatory from UT
9:00:31 (194 sec after the trigger) to UT 13:03 on November 18 2007.

We found a fading source at the position in the XRT error circle
reported by Moretti et al. (GCN 7111) in Rc and Ic bands. We made flux
calibration using NOMAD (for g' and Rc) and USNO B1.0 (for Ic) catalogs.
The photometric results are following.

   mid-UT            exp-T   g'     Rc         Ic
---------------------------------------------------------
2007-11-18  9:03:22   5min   >16.9  18.5+-0.5  >17.8
2007-11-18 10:12:12  25min   >19.1  19.1+-0.3  18.5+-0.3
2007-11-18 11:16:35  45min   >20.0  20.2+-0.3  19.7+-0.3
2007-11-18 12:33:20  57min   >20.3  20.7+-0.4  >20.2
---------------------------------------------------------