EXTRACTOR - An Astronomical Source Detection Program

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EXTRACTOR - An Astronomical Source Detection Program


EXTRACTOR is a program for automatically detecting objects on an astronomical image and building a catalogue of their properties. It is particularly suited for the reduction of large scale galaxy-survey data, but also performs well on other astronomical images.

EXTRACTOR is basically Emmanuel Bertin's SExtractor (Source-Extractor) program re-packaged for use with Starlink Software. This means that it uses the Starlink parameter system, accepts images in NDF format and uses the AST library for astrometry.

A largely unmodified version of SExtractor (2.5.0) is also included in the distribution of EXTRACTOR.

How to use EXTRACTOR

The latest version of EXTRACTOR is available in the EAO Starlink release.

Once you have this installed you should have a copy of the Starlink User Note SUN/226 available that describes EXTRACTOR. The command:

    % showme sun226

should display this in a web browser. After this you should consult the "Running EXTRACTOR" section.

To understand how EXTRACTOR works you'll need to consult the associated documentation (MUD/165 and the research paper). The Source Extractor for Dummies written by Benne Holwerda of the University of Cape Town is also available.

The GAIA program has an interactive environment for running EXTRACTOR and SExtractor. It displays the detection catalogue overlaid on the image (the figure shown above was created by GAIA). This is probably the easiest way to get started.

Bugs and fixes

For a list of bug and fixes in the current EXTRACTOR see the news file in the latest EAO release.

Questions or comments to: p.w.draper@durham.ac.uk.

Copyright © 2005 Central Laboratory of the Research Councils
Copyright © 2006 Particle Physics and Astronomy Research Council
Copyright © 2008-2009 Science and Technlogy Facilities Council
Copyright © 2009-2013 Peter W. Draper
Last modified: 02-Jun-2016
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