(fwd) Master Optical/Radio/Xray Catalogue (final version) now available on

[Andrzej Marecki]

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From: eric w flesch.org (Eric Flesch )
Subject: Master Optical/Radio/Xray Catalogue (final version) now available on 
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Announcing the final version of the Master Catalogue of Radio/Xray
Detections overlaid onto the Optical Background.  This version is
earmarked for the refereed process.  Changes are as follows:

Optical background:  The APM catalogue has recently been completed to
include the southern galactic cap, and these data have been added to
the optical background of the Master catalogue (which merges APM &
USNO).  Thanks to Mike Irwin for the final push to complete the
southern fields, and to Ray Stathakis for publishing that data on the
AAO website.  

Radio detections:  The FIRST and NVSS catalogues are found to have
astrometry at least as good as the APM, so field shifts for these are
restricted to corrections of the APM astrometry.  Thanks to Rick White
in clarifying issues involved in this.  Detection of double radio
lobes has been much improved in this version, and over 10,000 of these
are displayed.  These detections are reliable in this version,
compared with an admittedly cursory effort last time. 

Xray detections:  It is necessary to shift the ROSAT HRI, RASS, PSPC
and WGA fields over the optical background to find the correct
astrometry.  The method has been improved now to clean up recalcitrant
fields.  Whilst never perfect, the bulk of xray fields have been
aligned with good confidence.  

QSOs and AGN with optical APM/USNO signatures are included even if
they do not have radio/xray associations.  These include the SDSS
early data release and there are about 30,000 in total.  QSOs from old
papers from the 70's and 80's are now correctly identified using
improved likelihood algorithms.  There are about 200 such objects,
previously identified incorrectly, which are now assigned to the
correct optical object.

The Master Catalogue assigns probabilities to radio/xray objects that
they are QSOs, galaxies, stars, or erroneous associations.  This has
been refined via a decision tree algorithm, as well as the complete
APM data allowing better compensation against local sky densities.
The probabilities are calculated against a 670,000,000 object
whole-sky background database.

Get the Master Catalogue at ftp://quasars.org/quasars .  There is a
ReadMe there and smaller subset catalogs.  There will be some site
cleanup as this catalog goes to publication, so get the subset
catalogs now if you want them.  This version of the Master Catalogue
improves selection of about 15% of the objects compared with the
previous version, but the highest-probability QSO candidates are
mostly unchanged.

The SUMSS southern sky radio catalog is due for release any day now,
and I will update the Master Catalogue with that data when it is
available. 

Eric Flesch
Wellington, New Zealand
5 June 2002
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Andrzej Marecki                | 
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