TITLE: GCN CIRCULAR NUMBER: 12250 SUBJECT: Reprocessed enhanced Swift-XRT positions and GRB products DATE: 11/08/05 15:00:15 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports, The UK Swift Science Data Centre (http://www.swift.ac.uk) has reprocessed all the on-line GRB data products (XRT light curves, spectra, enhanced positions and the Burst Analyser) using the latest software and calibration. For light curves and spectra the differences between the new and previous results are small or negligible. By August 2011 our 90% confidence GRB enhanced positions were in agreement with UVOT OT positions in 80% of the cases. We have re-calibrated the UVOT-XRT mapping, updated our software to use a time-dependent mapping, and rebuilt the enhanced GRB positions; a new table is online at http://www.swift.ac.uk/xrt_positions. These new positions agree with those from the UVOT at the 90% level, thus verifying the enhanced position errors quoted. Note that the position changes are small, the median shift being 0.8 arcsec. For details of this reprocessing effort, see: http://www.swift.ac.uk/reprocessed.php