Naval Observatory, United States

a government scientific agency of the United States. It was established in 1842. It has (since 1964) a station in Flagstaff, Arizona, where there is a 60-inch (152-cm) reflector for astrophysical studies. The US Naval Observatory has a modernized 26-inch (66-cm) Clark reflector for photographic observations of double stars, a Markovitz lunar camera, a photographic zenith tube, and other equipment. The observatory compiles and publishes astronomical yearbooks for the navy and air force and an annual international reference work, Apparent Places of Fundamental Stars. It also serves as an international center of information on visually double and multiple stars.