TITLE: GCN CIRCULAR NUMBER: 16961 SUBJECT: GRB 141026A: Swift-XRT refined Analysis DATE: 14/10/26 17:51:04 GMT FROM: Phil Evans at U of Leicester V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), V. Mangano (PSU), P.A. Evans (U. Leicester), B.P. Gompertz (U. Leicester), J.P. Osborne (U. Leicester), A. Maselli (INAF-IASFPA) and L.M.Z. Hagen report on behalf of the Swift-XRT team: We have analysed 10 ks of XRT data for GRB 141026A (Hagen et al. GCN Circ. 16950), from 160 s to 46.2 ks after the BAT trigger. The data comprise 49 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. 16956). The late-time light curve (from T0+3.5 ks) can be modelled with a power-law decay with a decay index of alpha=0.35 (+0.11, -0.12). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.07 (+0.09, -0.08). The best-fitting absorption column is 4.9 (+/-0.5) x 10^21 cm^-2, in excess of the Galactic value of 1.6 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.92 (+0.28, -0.26) and a best-fitting absorption column of 2.8 (+1.2, -1.0) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (5.4 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.8 (+1.2, -1.0) x 10^21 cm^-2 Galactic foreground: 1.6 x 10^21 cm^-2 Excess significance: 2.0 sigma Photon index: 1.92 (+0.28, -0.26) If the light curve continues to decay with a power-law decay index of 0.35, the count rate at T+24 hours will be 0.023 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.9 x 10^-13 (1.2 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00616502. This circular is an official product of the Swift-XRT team.