[vsnet-grb-info 10829] Reprocessed enhanced Swift-XRT positions and GRB products

[GCN Circulars]

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  <pae9 at star.le.ac.uk>

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