5 Things to Know about the U.S. Naval Observatory

The U.S. Naval Observatory continues to be the leading authority in the United States for astronomical and timing data required for such purposes as navigation at sea, on land, and in space, as well as for civil affairs and legal matters.

The main building of the U.S. Naval Observatory in Washington, D.C., April 26, 2017. Completed in 1893, the building, designed by architect Richard Morris Hunt, houses the observatory's administrative department and is the headquarters of the Oceanographer and Navigator of the Navy. (U.S. Navy photo by Geoff Chester/Released)
The main building of the U.S. Naval Observatory in Washington, D.C., April 26, 2017. Completed in 1893, the building, designed by architect Richard Morris Hunt, houses the observatory’s administrative department and is the headquarters of the Oceanographer and Navigator of the Navy. (U.S. Navy photo by Geoff Chester/Released)

On this International Astronomy Day, here are 5 things to know about the observatory:

  1. The United States Naval Observatory (USNO) provides astronomical data that is critical for Positioning, Navigation, and Timing (PNT), a mission essential for the accurate navigation and communication of naval and DoD assets. The Naval Observatory, originally known as the Depot of Charts and Instruments, has been in operation since 1830.
  2. Astronomical observations are used extensively to prepare the Naval Observatory’s annual astronomical, nautical and air almanacs. The almanacs are essential for celestial navigation, which is currently the only viable alternative to GPS-based navigation in situations where GPS service is compromised.
  3. Today, the Naval Observatory is recognized around the world as the foremost authority in determining and disseminating the spatial and temporal reference frames that enable much of today’s digital technology and precision navigation.
  4. Nightly observations made at the Naval Observatory’s Flagstaff Arizona Station (NOFS) provide precise positions of planetary satellites, asteroids and other small solar system bodies. These observations are used extensively to navigate interplanetary spacecraft.
    The main building of the U.S. Naval Observatory's Flagstaff, Arizona Station (NOFS). It houses the observatory's largest telescope, the 1.55-meter Kaj Strand Astrometric Telescope. (U.S. Navy photo by Geoff Chester/Released)
    The main building of the U.S. Naval Observatory’s Flagstaff, Arizona Station (NOFS). It houses the observatory’s largest telescope, the 1.55-meter Kaj Strand Astrometric Telescope. (U.S. Navy photo by Geoff Chester/Released)
  1. Some of USNO’s contributions to current astronomical research and applications are below:

    Star Catalogs:
    USNO produces a variety of star catalogs for various applications. Its CCD Astrograph Catalog (UCAC) series provides precise positions, proper motions, and parallaxes of millions of stars in the visible part of the spectrum. The follow-on Robotic Astrometric Telescope Catalog (URAT, currently nearing completion) extends the UCAC’s capabilities to much fainter stars and provides the highest positional precision available in a ground-based catalog. These catalogs are important for Space Situational Awareness and are used to detect, identify and track unknown objects in Low Earth Orbit as well as Near Earth Asteroids and Potentially Hazardous Asteroids.  The Washington Double Star Catalog is a compiled catalog of long-term observations of double star systems, which make up the vast majority of visible stars. These observations are vital to the navigation of certain space-based assets such as geostationary satellites.Very Long Baseline Interferometry Catalogs: In collaboration with a number of radio observatories around the world, USNO collects and maintains data gathered through a technique for arraying widely-scattered radio telescopes known as Very Long Baseline Interferometry. Observations of thousands of extremely remote celestial radio sources known as “quasars” creates a fundamental reference frame against which all other objects in the universe can be measured. Using these data the motions of objects within our solar system, local star association, the Milky Way galaxy, and our parent galaxy cluster can be precisely determined. In addition, the instantaneous speed of Earth’s rotation, the precise angle of the planet’s rotational pole and other geophysical parameters can be precisely measured in near real-time.