Geometrical Ray-Tracing Calculations for a Space-Borne, Single-Aperture Astrometric Telescope Facility

Abstract

A 1.5 m telescope in space could achieve unprecedented differential astrometric precision, using essentially present-day technology. A Ronchi ruling in the prime focal plane moves over the images, and photoelectric detectors view the modulated starlight to determine angles between the target and reference stars within a 5 arcminute radius. A 10 microarcsecond precision can be achieved, after about an hour s integration time, for 13th magnitude targets. Such a telescope, operating over 20 years, could detect planets around nearby stars, and make major contributions to other stellar and galactic problems (Levy et al. 1986, 1987).