TITLE:   GCN CIRCULAR
NUMBER:  7370
SUBJECT: GRB080307: Optical upper limits
DATE:    08/03/07 15:59:54 GMT
FROM:    Michitoshi Yoshida at Okayama Astrophysical Obs  <yoshida@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 080307 (Holland et al. GCN 7362) with the
50cm MITSuME telescope at Okayama Astrophysical Observatory
from UT 11:25:50 to UT 12:47:00 on March 7 2008.

Flux calibration was made using USNO B1.0 catalog. We could
not identify any new source at the XRT position (Holland et al.
GCN 7362) or the UVOT positions (Schady et al. GCN 7367).
Three sigma upper limits are listed below.

mid-UT                exp.time     g'     Rc      Ic
-------------------------------------------------------
2008-03-07 11:31:20    10 min.   >19.6   >19.3   >18.7
2008-03-07 12:12:00    57 min.   >20.5   >20.3   >19.5
-------------------------------------------------------