TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3505
SUBJECT: GRB050528, XRT observations
DATE:    05/05/31 15:10:43 GMT
FROM:    Michael Goad at Leicester U  <mrg@star.le.ac.uk>

M. Goad (U. Leicester), J. Kennea (PSU), and D. N. Burrows (PSU) report on
behalf of the Swift XRT team:
 
We have analysed Swift XRT data from the soft burst GRB050528
(GCN3496, GCN3502).  The XRT was in an engineering mode at the time of the
burst and did not begin observations until it was switched back into its
normal observing mode.
Analysis of 15965 seconds (9 orbits) of Photon Counting mode data starting
14.15 hours after the BAT trigger reveals 3 faint sources within the BAT 3
arcmin error circle.
 
The source coordinates are :
 
RA(J2000)   23 34 03.7
Dec(J2000) +45 58 18.9
 
RA(J2000)   23 33 52.1
Dec(J2000) +45 57 40.2
 
RA(J2000)   23 34 03.2
Dec(J2000) +45 56 03.3

with an estimated uncertainty of 7 arcsecs radius.
 
Sources 1, 2 and 3 are located 122.1, 146.1 and 14.1 arcsecs from the
BAT position respectively.
 
Assuming a Crab like spectrum, photon index 2.1, and column density 1.2e21
cm-2 the observed count rates correspond to unabsorbed fluxes of 4.9e-14,
4.2e-14 and 3.2e-14 erg/cm2/s (0.5-10.0 keV), with an uncertainty of
1.2e-14 erg/cm2/s.
 
Due to the faintness of the sources, we cannot determine at this time
whether any of the sources are fading.