TITLE:   GCN CIRCULAR
NUMBER:  6975
SUBJECT: GRB071021: MITSuME Okayama Optical Upper Limits
DATE:    07/10/22 06:03:35 GMT
FROM:    Michitoshi Yoshida at Okayama Astrophysical Obs  <yoshida@oao.nao.ac.jp>

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

We observed the field of GRB071021 (Sakamoto et al., GCN6958)
with the three-color 50cm MITSuME Telescope at Okayama
Astrophysical Observatory. The observations started at 9:45:30
Oct. 21 UT (3m58s after the trigger). No new point source was
found in the XRT error circle of this burst (Barbier et al.,
GCN6966). The 3-sigma upper limits derived with the USNO B1.0
catalog are followings.

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      Mid time            Exp time        G     Rc     Ic
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2007-10-21  9:57:03   20min (60s x 20)  >19.4  >19.1  >18.7
2007-10-21 10:48:01   99min (60s x 99)  >20.3  >19.6  >19.3
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