TITLE:   GCN CIRCULAR
NUMBER:  4835
SUBJECT: GRB 060223B: Swift XRT possible afterglow
DATE:    06/02/25 21:22:25 GMT
FROM:    Matteo Perri at ISAC/ASDC  <perri@asdc.asi.it>

M. Perri, M. Capalbi, L. Vetere (ASDC) L.A. Antonelli (ASDC/INAF-OAR),
G. Tagliaferri (INAF-0AB), D.N. Burrows (PSU) and J.R. Cummings
(GSFC/ORAU) report on behalf of the Swift XRT team:

The Swift XRT began observing the field of GRB 060223B (trigger #192152,
Cummings et al., GCN 4821) at 2006-02-24 14:46:47 UT, approximately 19
hours after the BAT trigger. In a first XRT exposure of ~10 ks we find a
marginal detection (5 net photons, SNR=2) of a faint uncatalogued X-ray
source at the following coordinates:

RA(J2000) = 16h 56m 58.8s
Dec(J2000) = -30d 48' 46" is

with an estimated uncertainty  of 10 arcseconds (90% containment).
This position lies 30 arcseconds from the BAT refined position reported
by Fenimore et al. (GCN 4825).

The PSF corrected count rate is (7.5 +/- 3.9)e-4 cts/s, corresponding to
an unabsorbed 0.3-10 keV flux of about 5e-14 erg/cm2/s assuming a
power law spectrum with a photon index of 2 and Galactic absorption
of 1.8e21 cm^-2.

In a second exposure of  about 9 ks, starting ~29 hours after the
trigger, the source is not detected.

We note that due to the small number of counts this source could be
a statistical fluctuation of the background and should be regarded as
a possible X-ray afterglow candidate.

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