The U.S. Naval Observatory, founded in 1830, is responsible for providing the Navy, the Department of Defense, and the public with astrometric and timing data. Its mission includes maintaining the Master Clock for the United States, providing precise time, measuring the Earth's rotation, determining the positions and motions of the Earth, Sun, Moon, planets, stars, and other celestial objects, and providing astronomical data. The data from FAME will fulfill many needs of DoD, other government agencies, and the public at large for accurate astrometric data for the next two decades. The accurate star positions from FAME will enable autonomous space navigation systems to determine the positions of future satellites with accuracies better than 1 meter. More information on FAME can be found at the FAME web site .
Astronomers use the magnitude scale for describing the brightness of stars.
Stars with higher magnitudes are dimmer. The magnitude scale is logarithmic, a 10th magnitude star is 100 times fainter than a 5th magnitude star. The Asaph Hall Building, home of the USNO 26-inch Refracting Telescope Official USNO Illustrations.