EXTRACTORis a program for detecting and measuring the properties of all the sources on an astronomical image. It offers a large range of configuration options for controlling the way that objects are detected and the measurements that are made of them.
The source measurements are written to a catalogue (which can be of several different formats), so that they can be analysed (possibly by a catalogue handling package like CURSA – SUN/190).
EXTRACTOR, is based on the
SExtractor program which is described in the
SExtractor’s User Guide
(MUD/165). Consult this about all the various options that are available and for the rationale behind
Using this parameter you may give two image files. The first image will be used for detection and parameterising and the second will be used to actually measure the data values. Using this method allows you to measure the same objects many images, or to use a high signal to noise image to determine the measurement regions on a low signal to noise image
default.sexthat can be found in the directory
$EXTRACTOR_DIR/config. To modify the parameters used by this program, you must take a copy of this file and edit it. Guidance about the values that parameters can take may be found in this file as well as in the associated
SExtractordocumentation (see MUD/165).
The measurements made are determined by a list of parameters in the file
$EXTRACTOR_DIR/config/default.param. Again if you want measurements that are not available by
default, you must take a copy of this file and edit it. Remember to also change
default.sex to use this
file (otherwise you will continue to use the system-wide defaults).
One off modifications of parameters can be made using the KEYWORDS, NAME and VALUE parameters.
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