GCN Circular 4685
Subject
GRB060204a: Swift XRT Detection of an Afterglow Candidate
Event
Date
2006-02-06T07:38:45Z (20 years ago)
From
David Morris at PSU/Swift-XRT <morris@astro.psu.edu>
D. Morris (PSU), D. Burrows (PSU), N. Gehrels (GSFC), F. Marshall
(GSFC), M. Chester (PSU) on behalf of the Swift XRT team:
The Swift XRT began observing GRB 060204a, detected by INTEGRAL
(Mereghetti et al., GCN 4654), at 00:08:02 UT on 05 February 2006 (39 ks
after the burst trigger). In 14.5 ks of data, we find a faint,
uncataloged X-ray source within the 2.5 arcminute INTEGRAL error circle at:
RA(J2000): 15:28:58.4
DEC(J2000): -39:27:28.5
with an uncertainty of 5 arcsec (90% containment). This position
includes the latest XRT boresight correction and is 58 arcseconds from
the INTEGRAL reported position in GCN 4654. We calculate an average flux
for this source of 1e-13 ergs/cm2/s (0.2-10keV unabsorbed) assuming a
powerlaw index of 2 and galactic absorption of 1e21 cm^-2. We note that
this source flux is brighter than the 3-sigma upper limit reported in
GCN 4676 (Kong). Due to the small number of counts, we are unable to
determine whether the source is fading at this time. We note, however,
that the detected flux is consistent with typical GRB afterglow flux
levels at T+100ks, which is the mean epoch of this observation.
Observations are continuing and further analysis regarding the fading
nature of this source will be issued as the data become available.
This circular is an officical product of the Swift XRT Team.