Mount Lemmon Survey (MLS) is a part of the Catalina Sky Survey with observatory code G96. MLS uses a cassegrain reflector telescope (with 10560x10560-pixel camera at the f/1.6 prime focus, for a five square degree field of view) operated by the Steward Observatory at Mount Lemmon Observatory, which is located at in the Santa Catalina Mountains northeast of Tucson, Arizona.