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 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.