Just press the "Detect objects" button. This will by default find all the objects, create a catalogue of their positions, intensity and shape parameters, display the catalogue and finally get the catalogue window to draw some detection ellipses.
You can now use the catalogue window to investigate the results (see the help there for making selections).
The parameters shown in the various "pages" of the toolbox, control the values used in the detection and analysis of the objects on your image. These are directly related to the parameters used by the SExtractor program, the main and associated documentation (principally SUN/226 and MUD/165) should be consulted for their exact meaning.
Usually the meaning is obvious from the description in the short help (displayed at the bottom of the window), so you can proceed, at least initially, from just these.
When the toolbox starts up it configures itself by reading files called "default.sex" and "default.param". To locate these files it searches the following directories:
When it runs the toolbox updates the "default.sex" and "default.param" files (unless you've changed in names used). These can then be used to run SExtractor or EXTRACTOR. You can also use the File menu items to save the program and catalogue parameters to other files. So you can use the GAIA interface to fine tune the detection parameters for an image and then use these to do the detections on other images.
The toolbox always makes its measurements on the displayed image. If you want to use another image to do the initial detections then just enter its name in the "Detection image:" entry field.
If you want to stop plotting detection ellipses, then look under the "Options" menu and de-select the currently highlighted option.
The CHECK_APERTURES option (identified as the Aperture limits (fixed & Kron) option) produces ellipses which are the same as GAIA's Kron ellipses. Select these in the Options menu. Note that the default isophotal detection ellipses drawn by GAIA are based on the ISOAREA_IMAGE, ELONGATION and THETA_WORLD parameters, the ellipses have area ISOAREA_IMAGE.
To get a hardcopy of your image plus detections use the "Print..." item under the "File" menu in the main image window. Remember you only get a copy of what is visible, so if you have a large image unzoom it until it is all visible.
If you want to draw axes around your image then see the "Overlay axes grid..." item under the "Image-Analysis" menu in the main window.
To use your own version of SExtractor you need to define the environment variable EXTRACTOR_DIR to point to the directory that contains your "sex" program. Note this directory, or a sub-directory of it called "config" should contain the default SExtractor configuration files.
The toolbox was developed using a Starlink modified SExtractor version 2.2.1. Later versions may not be supported.
By default the toolbox will use the native version of SExtractor on FITS files. To stop this just open the "Options" menu and de-select the "Use Native SExtractor" item. You may need to do this if you have an image with a DSS astrometric solution and you want to measure sky coordinates.
To view your catalogue using a cut in the star/galaxy measurement parameter you need to use the catalogue window controls.
One way to do this is to sort by the "CLASS_STAR" column and just drag out all the objects you want to see (these will then be highlighted in the main window). The other way to do this is to copy the catalogue and open it twice in local catalogue windows. You can then use the catalogue window methods for selecting rows with values between given ranges (see the help in the catalogue window for how to do this).
The file types output by the toolbox are restricted to the following:
To read back a catalogue and display it as a series of detection ellipses you need to use the "Read old catalogue..." item in the "File" menu.
You can also read back catalogues as using the "Data-Servers" - "Local Catalogues" item on the main window. However it is unlikely that you'll get suitable ellipses drawn (this depends on whether your "skycat.cfg" file has been updated for this catalogue).
The "Options" - "Set Plot Symbols..." item in the catalogue window creates a dialog window in which you can define many things about the properties of any shapes that are drawn (these are Tcl expressions of the column names). To change the colour just choose a new one and apply it.