The Catalina Sky Survey (CSS)
is a survey of near-Earth objects,
i.e., comets and asteroids whose orbits
pass close to that of the Earth.
It was begun in 1998 and continues.
Its initial goal has been to identify 90%
of objects 1 kilometer or larger.
Two telescopes are used: 1.5-meter
telescope on Mt. Lemon and a 68-cm
telescope near Mt. Bigelow, both
near Tucson, Arizona.
The same data is used for the
Catalina Real-time Transient Survey (CRTS),
which scans the collected images for transients.
The CSS is the outgrowth of the earlier Bigelow Sky Survey (BSS),
which used photography.