TITLE: GCN CIRCULAR NUMBER: 15693 SUBJECT: GRB 140103A: Swift XRT afterglow confirmation DATE: 14/01/06 19:17:38 GMT FROM: Vanessa Mangano at PSU V. Mangano (PSU) reports on behalf of the Swift-XRT team: We have analysed 6.9 ks of XRT data for GRB 140103A (Mangano et al. GCN Circ. 15656), from 153 s to 59.7 ks after the BAT trigger. The data comprise 2.6 ks in Windowed Timing (WT) mode (the first 7 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. We confirm that the X-ray source reported in Mangano et al. GCN Circ. 15666 is the afterglow of GRB 140103A. Its light curve can now be modelled with an initial power-law decay with an index of alpha=0.18 (+0.17, -0.19), followed by a break at T+3221 s to an alpha of 1.18 (+0.51, -0.28). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.6 (+0.5, -0.4). The best-fitting absorption column is 2.5 (+1.9, -1.3) x 10^21 cm^-2, in excess of the Galactic value of 1.3 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 2.7 x 10^-11 (6.1 x 10^-11) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 2.5 (+1.9, -1.3) x 10^21 cm^-2 Galactic foreground: 1.3 x 10^20 cm^-2 Excess significance: 3.0 sigma Photon index: 2.6 (+0.5, -0.4) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00582773. This circular is an official product of the Swift-XRT team.