  We present a refined catalog for the positions of 179 Gamma-ray burst (GRB)
X-ray afterglows observed by the X-ray Telescope (XRT) on Swift prior to
November 1, 2006. The positions are determined by detecting X-ray field sources
in the deep X-ray images and comparing the centroids to those of optical
sources in the Digitized Sky Survey (DSS) red2 catalog or the Sloan Digital Sky
Survey (SDSS) DR-5 catalog. Half of the 90% confidence error region radii are
<2.2 arcseconds. The error regions areas are typically ~4 times smaller than
the best XRT-team error regions, although the positions require deep X-ray
integration (>20 ksec) and cannot be generated nearly as rapidly after the GRB.
The positions derived for >90% of 77 bursts with optical afterglows are
consistent with the optical transient positions, without the need for
systematic error. About 20% of the afterglows positions require a sizable shift
in the Swift satellite aspect. We discuss the optical/X-ray properties of the
field sources and discuss implications of the frame offsets for studies of
optically dark GRBs.
