A Dedicated 1-Meter Telescope for High Precision Astrometric Sky Mapping of Faint Stars

Requirements for future, ground-based, global, astrometric surveys are discussed. A new generation of catadioptric telescopes for high precision astrometric catalog work is described. Results of design studies for modified Richter-Slevogt optical systems with apertures of 0.5 to 1.0-m and aperture ratios ~ f /4 are presented. It is shown that these systems can be made nearly diffraction-limited with a field size up to 3° diameter and very small third-order distortion (≤ 1.0 arcsec/deg3). Because of their compact design (tube length ≤ 0.5 f) these telescope systems are optimal for automatic and remote operation. An example 0.9-m instrument could map a hemisphere with 4-fold overlap to 21th magnitude in one year, providing 10-mas positional accuracy for stars in the 15 to 19 mag range. The proposed design is applicable for dedicated photometric telescopes as well.