The Effect of Differential Color Refraction on Astrometric Observations of Solar System Bodies and Earth Satellites from Ground Based Optical Telescopes
MIT Lincoln Laboratory Lexington United States
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Earths atmosphere is optically dispersive and subjects astrometric observations from ground-based optical telescopes to systematic bias from differential color refraction DCR. This bias is evident in Minor Planet Center observations of asteroids with known spectral types and in observations of GPS and GLONASS satellites. DCR bias is on the order of 0.1 arcsec, and until recently, fixed-pattern star catalog errors exceeded this level. With the release of the Gaia DR2 star catalog in April of 2018, catalog error is no longer dominant and the systematic error floor in ground-based astrometry is defined by DCR.