TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5404 SUBJECT: GRB 060805: XRT Team Refined Analysis DATE: 06/08/05 16:59:13 GMT FROM: Kim Page at U.of Leicester K.L. Page, O. Godet (U Leicester) & H.Z. Ziaeepour (UCL-MSSL) report on behalf of the Swift-XRT team: We have analysed the first 4 orbits of the XRT data obtained for GRB 060805 (trigger 222683), comprising 8.4 ks of Photon Counting mode data between 101 s - 18.3 ks after the BAT trigger. Using these data, we obtain a refined position of: RA(J2000) = 14 43 43.59 Dec(J2000) = +12 35 13.2 with an uncertainty of 3.9 arcsec (90% containment). This is 47.9 and 1.4 arcsec from the initial BAT and XRT positions respectively (GCN Circ 5398; Ziaeepour et al). The X-ray afterglow is faint, with a count rate of ~0.1 count s^-1 at 100 seconds after the trigger. After the first orbit, during which the count rate was close to constant, the afterglow decays with a slope of alpha = 1.06 +/- 0.35. The spectrum (using the combined data from all 4 orbits) can be well fitted by a simple power-law, of Gamma = 2.39 +0.64/-0.51, with a total absorbing column of about 1e21 cm^-2 (compared to the Galactic column density of 1.57e20 cm^-2). During the first orbit (between 101 and 935 seconds after the trigger), the 0.3-10 keV unabsorbed flux was 4.72e-12 erg cm^-2 s^-1. If the afterglow continues to fade with alpha ~ 1.06, the count rate at 24 hours is predicted to be 1.6e-3 count s^-1, corresponding to an observed (unabsorbed) flux of 5.92e-14 (8.92e-14) erg cm^-2 s^-1. This circular is an official product of the Swift-XRT team.