TITLE: GCN CIRCULAR NUMBER: 16277 SUBJECT: GRB 140515A: Swift-XRT refined Analysis DATE: 14/05/15 23:58:11 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo, M. G. Bernardini (INAF-OAB), P. A. Evans (U. Leicester) report on behalf of the Swift-XRT team: We have analysed 7.1 ks of XRT data for GRB 140515A (D'Avanzo et al. GCN Circ. 16267), from 60 s to 13.6 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 enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 16270). The light curve can be modelled with a power-law decay with an initial decay index of alpha=2.5 (+0.5, -0.3). Then at T0+1100 s the light curve rises, reaching a count rate ~ 0.3 ct/sec. The remaining two orbits show irregular rate variations likely due to an underlying flaring activity, with a count rate ~ 0.3 ct/sec and ~ 0.1 ct/sec respectively. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.75 (+0.12, -0.11). The best-fitting absorption column is 1.7 (+3.2, -1.7) x 10^22 cm^-2, at a redshift of 6.32 (Chornock et al., GCN Circ. 16269), in addition to the Galactic value of 2.5 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 3.7 x 10^-11 (3.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 2.5 x 10^20 cm^-2 Intrinsic column: 1.7 (+3.2, -1.7) x 10^22 cm^-2 at z=6.32 Photon index: 1.75 (+0.12, -0.11) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00599037. This circular is an official product of the Swift-XRT team.