The Catalina Sky Survey (CSS) is a survey to discover near-Earth objects (NEOs), in particular potentially hazardous asteroids (PHAs) that may pose a threat of impact. The survey is conducted at the Steward Observatory's Catalina Station, which is located near Tucson, AZ. It is a NASA funded project.

CSS has discovered more than 45% of the more than 18,000 known NEOs. Additionally, the Catalina Real-Time Transient Survey (CRTS) imagery from CSS’s extensive sky coverage is being used to search for optical transient celestial phenomena including supernovae, variable stars, active galactic nuclei, blazars, and the like. For that reason, CSS is very popular also amongst professional and amateur variable star researchers.   

The Catalina Surveys Data Release 2 (DR2) consists of the Catalina Sky Survey (CSS) and the Catalina Real-time Transient Survey (CRTS). Important to note is that objects within 10-15 degrees of the Galactic plane will not have Catalina Surveys photometry. The same applies to objects below Dec ~-30 degrees or above Dec ~+65 degrees. Finally, objects brighter than V ~12 will not have good photometry.

Peranso makes use of data from the CRTS, see Drake, A.J. et al. First Results from the Catalina Real-time Transient Survey, 2009, ApJ, 696, 870. See also references here.

The CSS survey is funded by the National Aeronautics and Space Administration under Grant No. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program.  The CRTS survey is supported by the U.S.~National Science Foundation under grants AST-0909182.