TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5369 SUBJECT: GRB 060729: Swift-XRT refined analysis DATE: 06/07/30 05:21:51 GMT FROM: Dirk Grupe at PSU/Swift-XRT GRB 060729: Swift-XRT refined analysis D. Grupe (PSU) reports on behalf of the Swift/XRT team We have analyzed the first 5 orbits with a total observing time of 10.9 ks of Swift XRT data (2.3 ks in Windowed Timing and 8.6 in photon counting mode) of GRB 060729 (Grupe et al., GCN 5365). The Photon Counting mode image provides a refined XRT position: RA(J2000) = 06h 21m 31.29s, Dec(J2000) = -62d 22' 13.4" with an error of 3.5" (90% confidence). This position is 3.2" away from the preliminary XRT position reported in GCN 5365. The X-ray light curve displays the end of a giant flare (at the beginning of the XRT observation this flare had a count rate of 1000 counts/s) followed by a second flare at 174s after the burst. The afterglow shows a long late-time flare between 1 ks to 10 ks after the burst. We do not see a break in the light curve yet that allows us to give a reliable prediction of the flux for the next 24h. Right now the count rate is at a level of 0.3 counts s**-1 or a flux of about 1.5e-11 ergs s**-1 cm**-2. Spectral fits to the Windowed Timing mode data during the flare phase suggest a significant absorption column density in excess of the Galactic value (4.82e20 cm**-2). The later photon counting mode data after the flares can be fitted by a single power law model with a photon index Gamma = 2.14+0.15-0.14 and an absorption column density NH=1.0+/-0.3 e21 cm**-2. We also want to point out that this burst is also an optically bright burst (Immler 2006, GCN 5267). Even though it is only 2h away from the sun in RA, it is circumpolar for most southern observatories. We would like to encourage all southern observers to obtain a spectrum of this burst in order to determine its redshift. This circular is an official product of the Swift XRT Team.