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US Naval Observatory

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description US Naval Observatory Overview

The United States Naval Observatory is a federal scientific institution in Washington, D.C., founded in 1830 as the Depot of Charts and Instruments. It performs astrometry, measures Earth orientation, maintains astronomical reference data, and contributes to precise timekeeping for navigation, communications, defense, and scientific work. The observatory produces the USNO Master Clock time scale and works with other institutions in establishing Coordinated Universal Time and celestial reference systems.

help US Naval Observatory FAQ

What does the US Naval Observatory actually do?

The United States Naval Observatory performs astrometry—precise measurement of star positions—maintains astronomical reference data, measures Earth orientation, and operates the Master Clock for the Department of Defense. Its timekeeping role makes it critical for GPS synchronization and military navigation systems worldwide.

Can the public visit the US Naval Observatory?

The US Naval Observatory, located in northwest Washington, D.C., offers limited public tours on select evenings with advance reservations. Tours typically include views through telescopes and presentations about the observatory's scientific work, but security restrictions apply.

Where is the US Naval Observatory located and is it near the Vice President's residence?

The US Naval Observatory is located at 3450 Massachusetts Avenue NW in Washington, D.C. The Vice President of the United States has an official residence located on the observatory grounds, which has been the case since the 1970s.

Does the US Naval Observatory control GPS timing?

The US Naval Observatory provides the precise timing data that underpins the Global Positioning System. GPS satellites carry atomic clocks that are monitored and synchronized using reference time from the Naval Observatory's Master Clock system, ensuring accurate positioning for civilian and military users.

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