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GCN Circular 6193

GRB 070311: MITSuME Okayama Optical Observation
2007-03-11T14:26:37Z (17 years ago)
Michitoshi Yoshida at Okayama Astrophysical Obs <>
M. Yoshida, K. Yanagisawa, Y. Shimizu (OAO, NAOJ) and N. Kawai 
(Tokyo Tech) report on behalf of the MITSuME collaboration:

We performed optical imaging observation (g', Rc, and Ic) of the 
field of GRB 070311 (Mereghetti et al. GCN 6189) with 50cm MITSuME
telescope at Okayama Astrophysical Observatory from UT 10:11 to 
UT 12:03 on Mar.11 2007.

We coadded 76 CCD frames for each band. Exposure time of each frame
is 1 minute. We made flux calibration using USNO B1.0 catalg. No 
new source was found around the position of the IR source reported
by Covino et al. (GCN 6190) and the XRT source reported by Guidorzi
(GCN 6192).  Three sigma limiting magnitudes of our observation are
listed below. 

band   mid-UT          exp.time       upper limit 
g'     Mar. 11 11:07   76 x 1 min.    20.7 mag
Rc     Mar. 11 11:07   76 x 1 min.    21.0 mag
Ic     Mar. 11 11:07   76 x 1 min.    19.2 mag
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