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The USNO websites,,,,,, and are undergoing modernization efforts. The expected completion of the work and the estimated return of service is Fall 2020, subject to change due to potential impacts of COVID-19.

Astronomical Applications

Quartermaster Seaman with Sextant

This US Naval Observatory Website is undergoing modernization and will be offline starting Thursday, 24 October 2019. The expected completion of work and return of service is estimated as 30 April 2020. Please visit and submit a Requirements Form to the USNO PAO if the information you are seeking is not accessible via another means.



Data Services

Sun and Moon rise and set times, Moon phases, eclipses, seasons, positions of solar system objects, and other data

Astronomical Information Center

Background information on common astronomical phenomena, calendars and time, and related topics

Almanacs and Other Publications

Astronomical and navigational almanacs, special publications, research reports

Software Products

Computer almanac for PCs and Macs, and more

For DoD Users

USNO Master Clock Time
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