Corrections to Some Terms of Nutation Deduced from the Paris Astrolabe Observations

Abstract

Any error in the position of the Earth's axis of rotation in space gives an error in the equatorial coordinates of stars used in the reduction of latitude and time observations and consequently gives an error in the results of these observations. This may be due to an error in the classical terms of nutation or to the neglected nutation in space produced by the theoretically predicted nearly-diurnal wobble (Hough, 1895; Poincaré, 1910; Jeffreys, 1949; Molodensky, 1961; Toomre, 1974). A preliminary study of these errors in latitude and time observations was reported in a preceding paper (Capitaine, 1975), which was subsequently corrected for a minor sign error (Capitaine, 1977).