[vsnet-grb-info 4882] Swift XRT observation of GRB 070707

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6610
SUBJECT: Swift XRT observation of GRB 070707
DATE:    07/07/08 18:53:29 GMT
FROM:    Andy Beardmore at U Leicester  <apb at star.le.ac.uk>

A.P. Beardmore, K.L. Page (U. Leicester) and A. Parsons (GSFC) report on
behalf of the Swift XRT team:

On 2007 Jul 08 00:57:50UT the Swift XRT started observing the field of
the INTEGRAL burst GRB 070707 (Beckmann et al., GCN 6606; Gotz et al.,
GCN 6607). In a 3.8ks exposure photon counting mode image taken from
31.8 ks to 54.1 ks after the trigger, we detect a source at
RA, Dec = 267.7437, -68.9242, which is

RA(J2000)  =  17h 50m 58.49s
Dec(J2000) = -68d 55m 27.0s

with an uncertainty of 5.4 arcsec (90% containment). This is 36.3 arcsec
from the position reported by Gotz et al. (GCN 6607), and within their
error circle.

Using a circular extraction region of 10 pixels radius, we observe 26
total counts. Together with an estimated background level of 1.0
count in the extraction region, we find the 99.73% Bayesian
confidence level on the source count rate is 0.003 to 0.011 count s^-1.

However, with such a limited number of photons, it is impossible to
say at this stage whether the source is fading and if this is the X-ray
counterpart to the GRB.

This circular is an official product of the Swift XRT team.