GCN Circular 35128
A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 8.8 ks of XRT data for GRB 231117A, from 85 s to 223.3 ks after the BAT trigger. The data comprise 9 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=0.65 (+0.07, -0.06). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.81 (+0.17, -0.13). The best-fitting absorption column is consistent with the Galactic value of 6.1 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.1 (+/-3.8) x 10^20 cm^-2 Galactic foreground: 6.1 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.81 (+0.17, -0.13) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01197027. This circular is an official product of the Swift-XRT team.