Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 13, 713-716, 1995
© European Geosciences Union 1995
31 Jul 1995
Space physics coordinate transformations: the role of precession
M. A. Hapgood Abstract. Raw data on spacecraft orbits and attitude are usually supplied in "inertial" coordinates. The normal geocentric inertial coordinate system changes slowly in time owing to the effects of astronomical precession and the nutation of the Earth's rotation axis. However, only precession produces a change that is significant compared with the errors in determining spacecraft position. We show that the transformations specified by Russell (1971) and Hapgood (1992) are strictly correct only if the epoch-of-date inertial system is used. We provide a simple formula for estimating the error in the calculated position if the inertial system for some other epoch is used. We also provide a formula for correcting inertial coordinates to the epoch-of-date from the standard fixed epoch of J2000.0.

Citation: Hapgood, M. A.: Space physics coordinate transformations: the role of precession, Ann. Geophys., 13, 713-716,, 1995.
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