TITLE:   GCN CIRCULAR
NUMBER:  15135
SUBJECT: GRB 130828A: Swift XRT and UVOT observations  
DATE:    13/08/30 01:53:41 GMT
FROM:    Dirk Grupe at PSU/Swift-XRT  <dxg35@psu.edu>

Dirk Grupe (PSU), Craig Swenson, and Mike Siegel 
report on behalf of the Swift team:


Swift-XRT has observed the error circle of the Fermi/LAT GRB 
130828A (Vianello & Sonbas, GCN Circ 15128)
in a series of observations tiled on the sky. In 2.5 ks of data, 
beginning 105 ks after the Fermi/LAT trigger, we detect an 
uncatalogued X-ray source at RA, Dec = 259.73234, 27.99570 which 
is equivalent to:
 RA (J2000.0)  = 17h 18m 55.76s
 Dec (J2000.0) = +27d 59' 44.5"
with an uncertainty of 4.1 arcsec (radius, 90% confidence).
This source is within the LAT error circle given in GCN circular
15128).

At the present time we cannot determine whether the source is 
fading, therefore we cannot be certain whether this is the 
afterglow of GRB 130828A or a serendipitous source.

The source was detected in observations with target ID 00020292. 
The results of the automated XRT processing of this source are 
available at 
http://www.swift.ac.uk/xrt_products/TILED_GRB00018/20292/index_1.php

The Swift UVOT observed this field for 2.5 ks in the u filter.
There are two sources at the edge of the XRT error circle, one is a
Seyfert 1.9 galaxy, SDSS J171855.44+275947.4, which may be the
counter part of the X-ray source. However, the origin of the X-ray
source  is unclear at this point.


This circular is an official product of the Swift team.