Angles and Range: Initial Orbital Determination with the Air Force Space Surveillance Telescope (AFSST)
Abstract : The institution of a robust, comprehensive program of Space Situational Awareness (SSA) necessarily includes observations by ground-based optical and infrared (OIR) telescopes. The Air Force Space Surveillance Telescope (AFSST) has been proposed as a system of telescopes designed to address the ground-based component of comprehensive SSA. A hallmark of our definition of AFSST is that it be composed of inexpensive, replicable telescopes programmed to accomplish multiple surveillance programs, but designed to achieve the difficult design-driving task of accomplishing an uncued search for small objects in Low Earth Orbit (LEO). We discuss the configuration of AFSST and describe one technique by which AFSST simultaneously acquires angle and range data for accurate real-time determination of LEO orbital elements, even upon first detection of the object.
The Naval Observatory Merged Astrometric Dataset (NOMAD)
The U.S. Naval Observatory (USNO) announces the release of the first version of the Naval Observatory Merged Astrometric Dataset (NOMAD). The almost 100 GB dataset contains astrometric and photometric data for about 1.1 billion stars derived from the Hipparcos, Tycho-2, UCAC2, Yellow-Blue 6, and USNO-B catalogs for astrometry and optical photometry, supplemented by 2MASS near-infrared photometry. For each unique star the ”best” astrometric and photometric data are chosen from the source catalogs and merged into a single dataset. A sequence of priorities is followed and NOMAD contains flags to identify the source catalogs and gives cross-reference identifications. This first release of NOMAD is not a compiled catalog; that is, if a star is identified in more than 1 of the above mentioned catalogs, only 1 catalog entry is chosen. Thus the local and global systematic errors of the various source catalogs will be present in this version of NOMAD. All source catalogs astrometric data are on the International Celestial Reference System within the limitations of the source catalogs. For more information and data retrieval see our homepage www.nofs.navy.mil/nomad. Here is a screen capture of the NOMAD web interface. Sample Data Across the bottom of this poster paper a sample of the NOMAD catalog output for a field at α = 0 and δ = 0◦ is given. The data are retrieved from the web interface.
Galactic high-energy astrophysics ; High-accuracy timing and positional astronomy : lectures held at the Astrophysics School IV, organized by the European Astrophysics Doctoral Network (EADN) in Graz, Austria, 19-31 August 1991
This book addresses graduate students in astronomy and astrophysics. The first part is devoted to galactic high-energy astrophysics. It treats particle accelerations (including shocks), the interstellar medium and supernovae remnants, high-energy emissions from normal stars and accretion in close binaries. The second part deals with observations like pulsar timing, and its measurement with radioastronomical tools, and astrometry, as performed in the HIPPARCOS satellite program.