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 Emmanuel Bertin’s SExtractor
(Source-Extractor)
program1
re-packaged for use in the Starlink Software Environment (see SG/4). This means that it uses the
Starlink parameter system, accepts images in NDF format (see SUN/33) and uses the AST library
(SUN/210) for astrometry.
A slightly modified version of SExtractor
2.19.5 is also included in the distribution of
EXTRACTOR
. You can find details of SExtractor
’s operation, and how to configure it, in the
SExtractor
User’s Guide (which is issued as a Starlink Miscellaneous User Document, MUD
1652)
– you configure EXTRACTOR
in much the same way, although with some restrictions (see Section 6).
The SExtractor
home page – http://terapix.iap.fr/soft/sextractor
– offers more information,
such as a link to the SExtractor for Dummies.
In the Starlink release both EXTRACTOR
and SExtractor
do not offer the galaxy model fitting features
that the full SExtractor
builds do. This has been done to reduce the external package dependencies
required, also it isn’t clear how useful these abilities would be without also creating an NDF version of
PSFEx.
This document describes how to run EXTRACTOR
, and includes instructions for running SExtractor
from the Starlink distribution.
1BERTIN E. and ARNOUTS S., 1996, A&AS 117,393
2Note this document is still in draft, consequently you should read this in conjunction with the A&AS paper and the earlier SExtractor user document.