Restoration of the ASCA Source Position Accuracy

[Michael Arida <arida@milkyway.gsfc.nasa.gov>]

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We are pleased to announce a revised web page devoted to restoring the
full accuracy of your ASCA derived source coordinates:

 http://heasarc.gsfc.nasa.gov/docs/asca/coord/update.html

This page provides the documentation, data table, and software which
can be used for any ASCA observation to reduce the absolute pointing
uncertainty of the ASCA satellite by a factor of four.

The revised 90% error circle radius for SIS coordinates is then 12
arcseconds, consistent with pre-flight specifications, effectively
restoring the full ASCA pointing accuracy.

This result is based on a comprehensive calibration of the ASCA X-ray
pointing accuracy described in the ApJ paper "Restoration of the ASCA 
Source Position Accuracy" by Gotthelf, Ueda, Fujimoto, Kii, & Yamaoka 
to appear Nov 10 2000 (ApJ Vol 542).

Please note that this web page supersedes the preliminary updated
coordinate web page and provides greatly improved results.

If you find this work useful, kindly reference the above paper (not
the web page!).

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