TITLE: GCN CIRCULAR NUMBER: 7346 SUBJECT: GRB080229: Swift XRT refined analysis DATE: 08/03/01 12:39:34 GMT FROM: Jirong Mao at INAF-OAB GRB080229: Swift XRT refined analysis J.Mao, (INAF-OAB), A. Moretti (INAF-OAB), J. Canizzo (NASA/UMBC), C. Guidorzi (Univ. Bicocca & INAF-OAB), A, Beardmore (U Leicester) P. Evans (U Leicester) report on behalf of the Swift-XRT team: We have analysed the first 2 orbits of Swift-XRT data obtained for BAT GRB 080229 (trigger #304379, Cannizzo, et al., GCN Circ. 7335). The data consist of 149 s in Windowed Timing (WT) mode, starting 90 s after the BAT trigger and 8.34 ks in Photon Counting (PC) mode. The astrometrically corrected X-ray position is given in Beardomre et al. GCN 7324. The XRT light-curve shows a flare peaking few seconds after the beginning of the observation (103+/-2 s). The descending part of the flare can be fit by a power law with a slope of alpha1=4.45+/-0.09 up to a break at t1=192.4+/- 2.5 s, which is followed by a flat decay with a slope of alpha2=0.18+/-0.01. A second break is present at 2700+/-1000 s with alpha3=0.8+/-0.5 The spectrum formed from all the WT data can be modeled with a power-law of photon index Gamma = 2.88 ± 0.09, with an absorbing column of NH = (3.1 ± 0.2)e21 cm^-2 (in excess with respect to the Galactic value of 8.97e20 cm^-2). The spectrum formed from the PC data can be modeled with a power-law of photon index Gamma = 1.99 ± 0.07, with an absorbing column of NH = (3.1 ± 0.2)e21 cm^-2, which is in agreement with the WT one. If the light-curve continues to decay with a slope of 0.8, the afterglow at 24 hour will be still bright with an expected count rate of 0.3 count s^-1. This corresponds to an observed (unabsorbed) flux of 1.41E-11(2.2e-11) erg cm-2 s-1. This circular is an official product of the Swift-XRT team.