TITLE: GCN CIRCULAR NUMBER: 14317 SUBJECT: GRB 130315A: Swift-XRT refined Analysis DATE: 13/03/16 00:59:05 GMT FROM: Phil Evans at U of Leicester K.L. Page (U. Leicester), C. Pagani (U. Leicester), G. Stratta (ASDC), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M.C. Stroh (PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 10 ks of XRT data for GRB 130315A (Evans et al. GCN Circ. 14311), from 167 s to 29.4 ks after the BAT trigger. The data comprise 337 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The refined XRT position is RA, Dec = 157.54687, -51.79362 which is equivalent to: RA (J2000): 10 30 11.25 Dec(J2000): -51 47 37.0 with an uncertainty of 3.6 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=. A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.49 (+/-0.04). The best-fitting absorption column is 2.88 (+0.19, -0.18) x 10^21 cm^-2, in excess of the Galactic value of 2.3 x 10^21 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.1 (+/-0.3) and a best-fitting absorption column of 3.1 (+1.2, -0.8) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (6.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.1 (+1.2, -0.8) x 10^21 cm^-2 Galactic foreground: 2.3 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 2.1 (+/-0.3) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00551126. This circular is an official product of the Swift-XRT team.