TITLE: GCN CIRCULAR NUMBER: 4498 SUBJECT: GRB 060111B: Swift XRT refined analysis DATE: 06/01/12 18:37:21 GMT FROM: Matteo Perri at ISAC/ASDC M. Perri (ASDC), A. Moretti (OAB), D. N. Burrows (PSU), R. Fink (GSFC), M. Ajello (MPE) report on behalf of the Swift XRT team: We have analyzed the first 6 orbits of XRT data from GRB 060111B (trigger 176918, GCN 4487). A ~13 ks Photon Counting mode image provides a refined XRT position: RA(J2000) = 19h 05m 42.23s, Dec(J2000) = +70d 22m 35.8s with an uncertainty of 3.6 arcsec (90% containment). This position is 1.1 arcsec away from the on-board XRT position (GCN 4487) and includes the latest XRT boresight correction. This position is 45 arcsec from the refined BAT position (Tueller et al., GCN 4492) and 3.0 arcsec from the optical afterglow reported by Yanagisawa et al. (GCN 4496). The X-ray light curve can be fit with a broken power-law with an initial decay slope of -4.0+/-0.4, a break at T+139+/-7 s, and a post-break slope of -1.1+/-0.1. A power-law fit to the X-ray spectrum from T+88s to T+425s gave a photon index of 2.1+/-0.3 and a column density of (2.0+/-0.9)e21 cm**-2. We note the Galactic hydrogen column density in the direction of the burst is 7.1e20cm**-2. If the burst continues decaying at the current rate we estimate an XRT count rate of 0.004 counts/s at T+24hr, which corresponds to an observed 0.3-10.keV flux of 2e-13 ergs cm**-2 s**-1.