TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3790
SUBJECT: GRB 050813: Swift XRT afterglow localization
DATE:    05/08/13 12:28:59 GMT
FROM:    David Burrows at PSU/Swift  <dxb15@psu.edu>

D. C. Morris, D. N. Burrows, J. A. Kennea, J. L. Racusin, N. Cucchiara, A. 
Retter (PSU), and N. Gehrels (GSFC) report on behalf of the Swift XRT team:

The Swift XRT began observing the short burst GRB 050813 (Retter et al., 
GCN 3788) at 06:46:23, but was unable to obtain an on-board centroid due to 
the lack of any bright source in the field of view.  Analysis of the 
ground-processed data finds a very faint (~0.01 cps), uncataloged source in 
the first orbit of data at coordinates

RA(J2000) = 16:07:57
Dec(J2000) = +11:14:52

Because of the faintness of the source, we estimate an uncertainty of 10 
arcseconds radius in this preliminary position.

This object is not visible in the second orbit.  We therefore consider it 
to be the afterglow of the GRB 050813.  We note the similarity (in terms of 
the extreme weakness of the X-ray counterpart) with short burst GRB 050509B.