GCN Circular 6610
Subject
Swift XRT observation of GRB 070707
Event
Date
2007-07-08T18:53:29Z (18 years ago)
From
Andy Beardmore at U Leicester <apb@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.