1. Introduction to Footprint Services
There is much more to astronomical observations than just source catalogs.
For example, when working with multiple observations at different wavelengths,
knowing their precise coverages is just as important, e.g. to look for dropouts,
and can be very difficult in case of the most significant observations that are
often the most complex, as well. This functionality has been missing almost
entirely from the toolbox of many astronomers until today.
Footprint Services provide a high-level user interface and Web services for
dealing with astronomical survey
geometry of arbitrary complexity. Based on our high-performance spherical library,
we built this online public repository of footprints and preloaded it with the coverage of
some of the most widely used datasets today including, for example, the Sloan Digital Sky Survey
(SDSS) and the Galaxy Evolution Explorer (GALEX).
This Web based toolkit that enables advanced spatial searches
for regions of interest on the sky, Boolean operations on selected footprints
(union, intersection), on-the-fly visualization, and exact area computation.
We also provide an easy-to-use interactive footprint editor, as well as a simple
upload facility. The results of the searches and region manipulations can be saved
and published on the footprint server or downloaded in various formats including
ASCII and the VO compliant Space-Time Coordinate (STC) region representation.