TITLE: GCN CIRCULAR NUMBER: 8157 SUBJECT: GRB 080828: Swift-XRT detection of a possible X-ray afterglow DATE: 08/08/28 21:53:32 GMT FROM: Andy Beardmore at U Leicester A.P. Beardmore and R.L.C. Starling (U. Leicester) report on behalf of the Swift-XRT team: The Swift-XRT began observations of the field of the SuperAGILE detected GRB 080828 (Del Monte et al., GCN Circ 8151) at 2008-08-28 14:07:17UT, 39.15 ks after the burst. In 4.96 ks of photon counting mode data we detect a faint, uncatalogued X-ray source at RA, Dec 199.5871, -65.9405 which is RA (J2000) = 13:18:20.91 Dec (J2000) = -65:56:25.8 with an uncertainty of 4.2 arcsec (radius, 90% containment). This source is 1.1 arcmin away from the AGILE position and within its error circle. The measured XRT count rate is 0.008 +/- 0.001 count/s. At this stage we cannot tell whether the source is fading. This circular is an official product of the Swift-XRT team.