TITLE: GCN CIRCULAR NUMBER: 13249 SUBJECT: GRB 120422A: Swift-XRT refined Analysis DATE: 12/04/22 19:23:05 GMT FROM: Phil Evans at U of Leicester B. Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester) and E. Troja report on behalf of the Swift-XRT team: We have analysed 13 ks of XRT data for GRB 120422A (Troja et al. GCN Circ. 13243), from 101 s to 30.1 ks after the BAT trigger. The data comprise 307 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 13247). The light curve can be modelled with an initial power-law decay with an index of alpha=6.22 (+0.30, -0.28), followed by a break at T+373 s to an alpha of 0.30 (+0.11, -0.14). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 4.5 (+0.4, -0.3). The best-fitting absorption column is 2.5 (+0.5, -0.4) x 10^21 cm^-2, in excess of the Galactic value of 3.7 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 1.9 x 10^-11 (1.7 x 10^-10) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 2.5 (+0.5, -0.4) x 10^21 cm^-2 Galactic foreground: 3.7 x 10^20 cm^-2 Excess significance: 8.5 sigma Photon index: 4.5 (+0.4, -0.3) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00520658. This circular is an official product of the Swift-XRT team.