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A Brief History of the Naval Observatory


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Old USNO with Time Ball
The USNO time ball was one of the first systems to enable the Observatory
to support remote users. The ball was dropped at the astronomically determined
instant of Mean Solar Noon in Washington, which enabled the navigators of ships anchored in the Potomac River to rate their chronometers.

The U.S. Naval Observatory is one of the oldest scientific agencies in the country. It was established in 1830 as the Depot of Charts and Instruments. Its primary mission was to care for the U.S. Navy's chronometers, charts and other navigational equipment.

In 1844, as its mission evolved and expanded, the Depot was reestablished as the U.S. Naval Observatory and was located on a hill north of where the Lincoln Memorial now stands in Washington's Foggy Bottom district. For nearly 50 years the Observatory remained at the Foggy Bottom location. During these years significant scientific studies were carried out such as speed of light measurements, the phenomena of solar eclipses and transit of Venus expeditions. The astronomical and nautical almanacs were started in 1855. In 1877, while working for the Naval Observatory, astronomer Asaph Hall discovered the two satellites of Mars.


However, by the 1890's, it was clear that the Naval Observatory had to move out of the city. Unhealthy conditions in the Foggy Bottom neighborhood had taken their toll. In 1893, after nearly 50 years at the site on the Potomac River, the U.S. Naval Observatory moved to its present location in the hilly terrain north of Georgetown. At that time, this rural site was well outside the city in the countryside above Georgetown. The move not only provided better astronomical observing conditions, but also provided an opportunity to rethink old scientific programs and propose new ones. Along with the new programs such as daily monitoring of solar activity, the old functions of time keeping and telescopic observations were kept intact when the Observatory moved to the new site. The old Observatory in Foggy Bottom was declared a National Historic landmark in 1966 and is the current home of the Navy's Bureau of Medicine and Surgery (BUMED).

Today, the U.S. Naval Observatory is the preeminent authority in the areas of time keeping and celestial observing; determining and distributing the timing and astronomical data required for accurate navigation and fundamental astronomy.

A more extensive history of the Observatory may be found here.

The definitive history of the U.S. Naval Observatory is the book Sky and Ocean Joined: The U.S. Naval Observatory 1830 - 2000 by Steven J. Dick (Cambridge, UK, Cambridge University Press, 2002, ISBN 0 521 81599)

USNO Master Clock Time
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