GCN Circular 11721
G. Stratta (ASDC) and V. D'Elia (ASDC) report on behalf of the Swift-XRT team: We have analysed 22 ks of XRT data for GRB 110213A (D'Elia et al. GCN Circ. 11705), from 81 s to 54.5 ks after the BAT trigger. The data comprise 121 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN. Circ 11712). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=5.2 (+0.5, -0.4). At T+141 s the decay flattens to an alpha of -0.22 (+0.10, -0.14). The light curve breaks again at T+1489 s to a decay with alpha=1.10 (+0.07, -0.08), before a final break at T+9954 s s after which the decay index is 2.14 (+0.10, -0.09). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.11 (+/-0.07). The best-fitting absorption column is 2.81 (+0.24, -0.23) x 10^21 cm^-2, in excess of the Galactic value of 2.2 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (6.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.81 (+0.24, -0.23) x 10^21 cm^-2 Galactic foreground: 2.2 x 10^21 cm^-2 Excess significance: 20.5 sigma Photon index: 2.11 (+/-0.07) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00445414. This circular is an official product of the Swift-XRT team.