TITLE: GCN CIRCULAR NUMBER: 11446 SUBJECT: GRB 101204A: Swift-XRT refined Analysis DATE: 10/12/09 16:38:18 GMT FROM: Boris Sbarufatti at INAF-OAB/IASFPA B. Sbarufatti (INAF/OAB-IASF Pa) reports on behalf of the Swift-XRT team: We have analysed 24 ks of XRT data for GRB 101204A (Cummings et al. GCN Circ. 11440), from 126.2 ks to 383.1 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. Using 9912 s of PC mode data and 4 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 = 167.53700, -20.41980 which is equivalent to: RA (J2000): 11h 10m 8.88s Dec(J2000): -20d 25' 11.5" with an uncertainty of 1.6 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=1.33 (+0.24, -0.23). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.14 (+0.34, -0.18). The best-fitting absorption column is consistent with the Galactic value of 3.3 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 3.4 x 10^-11 (3.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.3 (+4.4, -0.0) x 10^20 cm^-2 Galactic foreground: 3.3 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 2.14 (+0.34, -0.18) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020153. This circular is an official product of the Swift-XRT team.