POINTS: A Global Reference Frame Opportunity

  • J. F. Chandler
  • R. D. Reasenberg
Part of the International Astronomical Union / Union Astronomique Internationale book series (IAUS, volume 141)

Abstract

POINTS is a space-based optical astrometric interferometer, capable of measuring the angular separation of two stars about 90° apart with 5-microarcsec (μas) nominal accuracy. During the intended ten-year mission, a repeated survey of a few hundred targets over the whole sky, including a few bright quasars, will establish a “rigid” reference grid with 0.5 μas position uncertainties. At that level, the grid will be free of regional biases and tied to the extra-Galactic frame that is our present best candidate for an inertial frame. POINTS will also determine parallaxes and annual proper motions at about the same level. Further, the planetary ephemeris frame will be tied through stellar aberration to the grid at about 300 μas. Additional targets of interest, to a limiting magnitude of greater than 20, will be observed relative to the grid, yielding determinations with uncertainties depending on the observing schedule. Measurement at the microarcsec/year level of the apparent relative velocities of quasars that are widely separated on the sky will severely test the assumption of cosmological quasar distances and may also constrain models of the early Universe.

Keywords

Proper Motion Hubble Space Telescope Reference Star Extragalactic Radio Source Very Large Array 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© IAU 1990

Authors and Affiliations

  • J. F. Chandler
    • 1
  • R. D. Reasenberg
    • 1
  1. 1.Smithsonian Astrophysical ObservatoryCambridgeUSA

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