User manual

Tip: The properties window associated to a contour plane (menu: Edit => Properties) lets
you adjust the levels and colours of each contour afterwards.
5.5Dealing with catalogue filters
Button filter
Menu: catalogue => Create a filter…
Filtering catalogues in Aladin is a powerful tool to visualise sources in a clever way.
Default behaviour (no filter)
By default, Aladin displays sources with graphical symbols, all the same symbols for a
given plane (shape and colour). The shape is a function of the source number (smaller
symbols for denser catalogues). Colour and shape can be modified afterwards by using
the measure values associated to each source. To do so, you need to use what is called a
“filter” in Aladin.
Filter definition
In Aladin, a filter will be applied to
one or several catalogue planes in
order to modify the way graphical
symbols are displayed in the view. It
works with one or several rules that
will indicate to Aladin how to draw
sources with respect to values given
in the source measures. Hence, it will
be possible to plot circles that are
proportional to the magnitude,