TITLE: GCN CIRCULAR NUMBER: 13687 SUBJECT: GRB 120819A: Swift-XRT refined Analysis DATE: 12/08/20 05:47:04 GMT FROM: Phil Evans at U of Leicester O.M. Littlejohns (U. Leicester), V. D'Elia (ASDC), A. Maselli (INAF-IASFPA), V. Mangano (INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), M.C. Stroh (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and A.P. Beardmore report on behalf of the Swift-XRT team: We have analysed 10 ks of XRT data for GRB 120819A (Beardmore et al. GCN Circ. 13681), from 159 s to 23.0 ks after the BAT trigger. The data comprise 67 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 13684). The light curve can be modelled with a power-law decay with a decay index of alpha=1.75 (+0.12, -0.09). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.7 (+/-0.4). The best-fitting absorption column is 3.3 (+2.0, -1.5) x 10^21 cm^-2, in excess of the Galactic value of 8.9 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 4.2 x 10^-11 (6.0 x 10^-11) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 3.3 (+2.0, -1.5) x 10^21 cm^-2 Galactic foreground: 8.9 x 10^20 cm^-2 Excess significance: 2.6 sigma Photon index: 1.7 (+/-0.4) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00531428. This circular is an official product of the Swift-XRT team.