TITLE: GCN CIRCULAR NUMBER: 15292 SUBJECT: GRB 131002A: Swift-XRT refined Analysis DATE: 13/10/02 19:30:03 GMT FROM: Phil Evans at U of Leicester K.L. Page (U. Leicester), C. Pagani (U. Leicester), B. Sbarufatti (INAF-OAB/PSU), 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 report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team: We have analysed 6.5 ks of XRT data for GRB 131002A, from 56 s to 29.9 ks after the BAT trigger. The data comprise 44 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The late-time light curve (from T0+5.1 ks) can be modelled with a power-law decay with a decay index of alpha=1.05 (+0.26, -0.24). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.03 (+0.19, -0.18). The best-fitting absorption column is 1.0 (+0.5, -0.4) x 10^21 cm^-2, in excess of the Galactic value of 5.6 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 3.6 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.0 (+0.5, -0.4) x 10^21 cm^-2 Galactic foreground: 5.6 x 10^20 cm^-2 Excess significance: 1.9 sigma Photon index: 2.03 (+0.19, -0.18) If the light curve continues to decay with a power-law decay index of 1.05, the count rate at T+24 hours will be 7.7 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.8 x 10^-13 (3.6 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00572721. This circular is an official product of the Swift-XRT team.