A Note on the Astrometric Precision of Minor Planet Observations

Abstract

AbstractFor years, interest in precise positions of minor planets has centered on tying the dynamical reference frame with the stellar frame and determining catalog zone errors. Photographic methods are generally used in obtaining observed spherical equatorial coordinates (R.A., Dec.) or crossing-point observations. Estimates of the external precision of the equatorial coordinates are overly pessimistic, while those for crossing-point observations, too optimistic.It is estimated that equatorial positions for the brighter (m < 11) minor planets can be determined with an external precision not worse than +/−0.2 arcsec (m.e.), and perhaps as low as +/−0.1 arcsec (m.e.), depending on the reference catalog zonal errors.Intersatellite observations are a type of crossing-point observation in which the images of two different objects appear in the same exposure. This is the most precise type of crossing-point observation and gives an estimate for the lower limit to the external precision of this observation type. Recent studies of satellite observations indicate that this lower limit is in the +/−0.05 to +/−0.08 arcsec (m.e.) range.