GCN Circular 3083
Subject
GRB050309: Early optical limit from P60
Event
Date
2005-03-10T06:49:44Z (21 years ago)
From
Derek Fox at CIT <derekfox@astro.caltech.edu>
Derek B. Fox and S. Bradley Cenko report on behalf of the
Caltech-NRAO-Carnegie GRB collaboration:
"Examination of a coadded R-band image from our P60 observations for
the BAT localization region of GRB050309 (Barthelmy et al, GCN 3082),
taken at a mean epoch of 10:55 UT (12 minutes after the burst),
confirms our earlier report (Cenko & Fox, GCN 3080) of the absence of
new optical sources to the limit of the Digitized Sky Survey and our
own observations. We estimate this limit to be R < 20.5 mag as
calibrated against the USNO B-1.0 catalog magnitudes of bright stars
in the region.
This limit applies to XRT source #2 (GCN 3082), where no emission is
seen. The position of XRT source #1 is 6-arcsec (twice the FWHM in
our images) from a bright star and USNO B-1.0 catalog object having
R=12.98 mag. No extension of the catalog star is apparent in our
images."