Astrometry

An all-sky image generated from the USNO-A catalog. What is shown is the number of stars per square degree. Yellow corresponds to the highest density, and dark blue to the lowest. The yellow band across the middle of the image is the plane of our galaxy. Dark areas superimposed on the central band are clouds of dust and gas which obscure some of the stars from view. The two bright blobs below and to the right of center are the Magellanic Clouds.

Astrometry is the branch of astronomy concerned with the determination of positions, proper motions, and parallaxes of solar-system bodies, stars, and distant galaxies.  Astronomers at USNO use the latest instrumentation and methods to extend the accuracy and brightness limits of astrometric catalogs and reference frames.

• Optical/IR Products
  

  Optical/infrared image and catalog products provided by the USNO.  Astrometric catalogs include NOMAD, UCAC, USNO-B1, Double Stars, etc.  Imaging products include digital scans of a number of the major Schmidt telescope surveys of the skies, along with the catalogs of astronomical objects created from those images.  Access to astrometric catalogs and imaging products is provided through the USNO Image and Catalog Archive Server.

• VLBI-based Products

  Very Long Baseline Interferometry (VLBI) is a technique used by radio astronomers and geodesists to determine the celestial and terrestrial reference frames and to predict the variable orientation of the Earth in three-dimensional space.  Access to VLBI images is available through the Radio Reference Frame Image Database.

• Astrometry Information Center

  Your one-stop-source for astrometry related information.