The Celestial Reference Frame (CRF) activity of the U.S. Naval Observatory (USNO) is responsible for the determination of the positions, motions, and other physical properties of celestial objects and the establishment of the celestial reference frame for the Navy, Department of Defense, and U.S. Government.

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The United States Naval Observatory

The US Naval Observatory is one of the oldest scientific agencies in the United States with the primary mission to produce foundational position, navigation, and timing (PNT) data for the U.S. Navy and the U.S. Department of Defense.

The headquarters are located in Washington, DC. The current site, established in 1893, includes the DOD Master Clock and the nearly 150-year-old “Great Equatorial” telescope, shown above, which is still in everyday operational use collecting CRF data.

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Naval Observatory, Flagstaff Station (NOFS, shown above), established in 1955, is USNO’s primary dark sky observatory site. Instrumentation includes the 61 inch Kaj Strand Telescope and the Navy Precision Optical Interferometer (NPOI), located on nearby Anderson Mesa.

These webpages provide information on the roles and responsibilities that USNO has to the national and international communities as well as our products that are used by the astronomical and geodetic communities. These webpages are organized so that users are able to find information related to specific areas of research or interests. The site tree for all of our pages is located on the left side and can be used to easily navigate between different areas.

USNO's CRF responsibilities include hosting four international astronomical centers of expertise: information about USNO's Double Star activity, including products such as the Washington Double Star Catalog, can be found under the "IAU Double Star Center"; information about the Internation Celestial Reference System can be found under the "IERS ICRS Center"; Very Long Baseline Interferometry (VLBI) information and products can be found under "IVS Analysis Center"; and information and data products related to reference frame objects can be found in the Fundamental Reference Image Data Archive (FRIDA), under the "IVS Analysis Center for Source Structure". All of our data products found throughout these pages are also accessible under "Data Products".