TITLE: GCN CIRCULAR NUMBER: 6521 SUBJECT: GRB 070612B: Swift-XRT refined analysis DATE: 07/06/12 20:01:19 GMT FROM: Dirk Grupe at PSU/Swift-XRT D. Grupe (PSU) reports on behalf of the Swift/XRT team We have analyzed two orbits of GRB 070612B (Grupe et al., GCN 6509) with total observing times of 4.7 ks in Photon Counting mode in the Swift XRT. Due to Earth-constrain Swift did not slew immediately and XRT observations were delayed by almost one hour (Grupe \& Evans, GCN 6514). The Photon Counting mode image provides a refined XRT position at Ra, Dec= 261.7271, -8.7517, which is RA(J2000) = 17h 26m 54.49s Dec(J2000) = -08d 45' 06.3" with an error of 4.0" (90% confidence). This position is 2.7 " away from the preliminary XRT position reported in GCN 6514. The X-ray light curve shows a decaying source. While the afterglow is clearly detected in the first orbit, only a 3sigma upper limit of 0.012 counts/s can be given for the second orbit. Based on this result, we estimated a decay slope of 2.8+/-0.6. The X-ray data can be fitted by a single power law with a photon index Gamma=1.7+-0.8 and the absorption column density fixed to the Galactic value of NH=1.68e21 cm-2 (Dickey & Lockman, 1990) with chi2/dof=4/3. This circular is an official product of the Swift XRT team.