TITLE: GCN CIRCULAR NUMBER: 13453 SUBJECT: GRB 120711B: Swift-XRT refined Analysis DATE: 12/07/12 05:58:14 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) and M. J. Page (UCL-MSSL) report on behalf of the Swift-XRT team: We have analysed 4.5 ks of XRT data for GRB 120711B (Page et al. GCN Circ. 13431), from 208 s to 47.2 ks after the BAT trigger. The data comprise 106 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. Using 551 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 331.69137, +60.02267 which is equivalent to: RA (J2000): 22h 06m 45.93s Dec(J2000): +60d 01' 21.6" with an uncertainty of 1.8 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=1.69 (+0.22, -0.17). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.8 (+0.5, -0.4). The best-fitting absorption column is 2.4 (+0.9, -0.8) x 10^22 cm^-2, in excess of the Galactic value of 7.2 x 10^21 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.5 (+0.4, -0.3) and a best-fitting absorption column of 2.9 (+0.7, -0.6) x 10^22 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 9.9 x 10^-11 (1.7 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.9 (+0.7, -0.6) x 10^22 cm^-2 Galactic foreground: 7.2 x 10^21 cm^-2 Excess significance: 5.6 sigma Photon index: 1.5 (+0.4, -0.3) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00526270. This circular is an official product of the Swift-XRT team.