-- forwarded message -- Newsgroups: sci.astro.research Path: mat.uni.torun.pl!news.man.torun.pl!news.man.poznan.pl!news-fra1.dfn.de!news-lei1.dfn.de!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!newspeer1-gui.server.ntli.net!ntli.net!newspeer.clara.net!news.clara.net!server3.netnews.ja.net!bath.ac.uk!unknown From: eric@flesch.org (Eric Flesch ) Subject: Master Optical/Radio/Xray Catalogue (final version) now available on Approved: sci.astro.research-request@slimy.greenend.org.uk (mjh) Sender: unknown@scorpius.star.bris.ac.uk (Address not verified) Organization: Orcon Internet Message-ID: mt2.0-4318-1023269017@star.bris.ac.uk X-Posting-Tool: modtool v2.0 Date: Wed, 5 Jun 2002 09:23:20 GMT Lines: 55 Xref: mat.uni.torun.pl sci.astro.research:1433

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 -- end of forwarded message --