TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3527
SUBJECT: Optical Afterglow of GRB 050607
DATE:    05/06/07 13:16:16 GMT
FROM:    James Rhoads at STScI  <rhoads@stsci.edu>

James Rhoads reports on behalf of a larger collaboration:
I observed the field of GRB 050607 with the 4m Mayall Telescope
at Kitt Peak, starting on 2005 June 7 UT 09:20:46.
Observations continued until morning twilight at 11:18 UT.

We detect a faint, fading optical source located at
20:00:42.79 +09:08:31.5 (J2000), about 8 arcseconds
from the XRT source.
We calibrated astrometry to the nearby USNO star, located
at 20:00:42.70 9:08:35.0.  Our *relative* astrometry
should be good to < 0.5".

The approximate I band magnitude is 22.65 (statistical error
is 0.1 mag, systematic error is 0.2-0.3 mags) in our first 
exposure, which was 150 seconds commencing 563 seconds
after the burst.

Further analysis of the multiwavelength data set is in progress.