TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5599 SUBJECT: GRB 060923A: Swift XRT refined analysis DATE: 06/09/23 19:14:02 GMT FROM: Maria Laura Conciatore at ASDC M.L. Conciatore, M. Capalbi, M. Perri, D.N. Burrows (PSU) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift XRT team: We have analysed the first five orbits of Swift XRT data from GRB 060923A (Stamatikos et al., GCN 5583). A ~2.5ks PC mode image provides a refined X-ray position of: RA(J2000) = 16h 58m 28.2s Dec(J2000) = +12d 21' 40.0" with an uncertainty of 6.0 arcseconds radius (90% containment).This is 3.4 arcseconds from the XRT position given by Stamatikos et al.(GCN 5583) and 74.8 arcsec from the refined (ground-calculated) BAT position (Tueller et al., GCN 5589). This position is 1.14 arcseconds from the detected source reported by Tanvir et al. (GCN 5587), and 1.32 arcseconds from the one reported by Fox et al. (GCN 5597) as a candidate counterpart afterglow. X-ray light curve shows an initial power-law decay with a decay index of 2.7+/-0.3. Then, after a slow rebrightening starting at ~650s, from T+4200 the source decays with a slope of 1.23 +/-0.1. An absorbed power-law fit to the X-ray spectrum from T+100s to T+960s gave a photon index of 2.1+/-0.2 and a column density of (1.2+/0.1)e21 cm**-2. We note the galactic hydrogen column density in the direction of the burst is 5.1e20 cm**-2. The 0.2-10.0 keV observed flux for this spectrum is 4.1e-11 ergs cm**-2 s**-1, which corresponds to an unabsorbed flux of 4.9e-11 ergs cm**-2 s**-1. Assuming that the X-ray emission continues to decline at the same rate, we predict a 0.2-10 keV XRT count rate of 0.006 count/s at T+24hr, which corresponds to an observed 0.2-10 keV flux of 2.4e-13 erg/cm**2/s. This circular is an official product of the Swift XRT Team. [GCN OPS NOTE(24sep06): Per author's request, the author list was added.]