High Quality Content by WIKIPEDIA articles! The United States Naval Observatory Flagstaff Station (or NOFS), is a scientific astronomical observatory operated as a Navy Echelon V command and the national dark-sky observing Facility/observatory subordinate to the United States Naval Observatory (USNO). USNO (itself an Echelon IV command) and NOFS are commands within the CNMOC claimancy, the latter which serves the U.S. Navy on meteorological and oceanographic matters in addition to overseeing astronomical ones. The Flagstaff Station is a command which was established by USNO (due to a century of eventually untenable light encroachment in Washington, D.C.) at a site five miles west of Flagstaff, Arizona in 1955, and has positions for 35 scientists (astronomers and astrophysicists), optical and mechanical engineers, and support staff. It is currently manned at 20 personnel. Its principal mission is to provide the military and others extremely accurate, ground-based astrometry (defined as the positions of celestial and artificial space objects) and photometry (defined as brightness variations, often in terms of `color`) – in the form of million-to-billion-star catalogs for a wide diversity of U.S. global (and spaceborne) position and navigation interests. NOFS specializes in extremely faint-magnitude, extremely accurate observations which cannot normally be obtained from space telescopes, and remains the most respected astrometric observatory in the world. NOFS remains the senior U.S. Navy facility/unit in the state of Arizona.