In addition to images, GCX handles lists of astronomical objects
generally referred to as stars. There are several types of
stars, and the various types have different kinds of information
attached. They can be grouped in two classes: A relatively
straight-forward star detection algorithm is implemented in GCX.
It will search for local intensity peaks that satisfy the
following conditions: The star detection routine is called by
selecting Stars/Detect Sources, or automatically by other
operations (WCS fitting and frame alignment). The detection
routine will produce detected stars, except when called on an
alignment reference frame, in which case it will produce
alignment stars. Another way of creating frame stars is to
control-click on or near an otherwise unmarked star image. This
will initiate a spiral star search in a region around the the
cursor, with the SNR parameter set to a low value (3.0). In this
way, even very faint stars that are located near the cursor can
be marked. This procedure creates user s