[vsnet-grb-info 1724] GRB 050626: Swift XRT observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3564
SUBJECT: GRB 050626: Swift XRT observations
DATE:    05/07/05 17:34:19 GMT
FROM:    David Burrows at PSU/Swift  <dxb15 at psu.edu>

V. Mangano, T. Mineo, V. La Parola, G. Cusumano (INAF-IASF/Palermo),
S. Hunsberger (PSU), D. Morris (PSU), A. Beardmore, K. Page (U. Leicester),
P. Boyd (GSFC-UMBC), L. Angelini (GSFC-JHU)
and D. N. Burrows (PSU) report on behalf of the Swift XRT team:

Swift observed GRB 050626 (D. Gotz at al, GCN3552) with XRT in Photon 
Counting (PC) mode for three times starting between 2005-06-29 03:38:54 and 
2005-07-01 12:10:42 and collected a total of 38.6 ks. (Observations were 
delayed by several days because the Integral source was initially located 
near the Swift orbital pole, and was within the Swift Earth avoidance 
angle.)  The three observations were performed in manual state to avoid the 
automatic switching in Windowed Timing (WT) mode caused  by the presence of 
two bright optical stars within 3 arcmin of the INTEGRAL position.

Only one uncataloged X-ray source was detected within the INTEGRAL error 
circle, at

RA(J2000) = 12h 27m 01.2s  Dec(J2000) = -63:08:13.9,

i.e. 20 arcsec from the INTEGRAL position.  The count rate of this source 
has been found to be steady within errors at the average level of (1.6 +/- 
0.4)E-3 counts/s, making it unlikely to be the X-ray afterglow of the GRB.

No afterglow candidate was detected within the INTEGRAL error circle.
We estimate 3 sigma upper limits of 7.9E-14, 6.6E-14, and 1.6E-13
erg cm-2 s-1 for the flux of the GRB afterglow in the first, second and third
observations, respectively and a 3 sigma upper limit of 3.8E-14 erg cm-2 s-1
in the sum of the three observations.