Accession Number:

ADA063376

Title:

Compression of Ephemerides by Discrete Chebyshev Approximations.

Descriptive Note:

Final rept.,

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON D C

Report Date:

1979-01-04

Pagination or Media Count:

23.0

Abstract:

Polynomial representations of astronomical ephemerides are usually derived from discrete least-squares approximations. Ideally, to ensure a uniform distribution of the error, one should aim at a continuous Chebyshev approximation. This is feasible when the ephemeris is generated from a literal analytical or semianalytical development. But a discrete Chebyshev approximation is a realistic compromise. Application to the moon and geosynchronous satellites has given good results. On the whole, long ranges several times the sidereal period may be covered by polynomials of degree 30 to 50 with a moderate error. A low-degree approximation over half the period usually delivers a high accuracy. Gibbs phenomena, i.e. rapid oscillations of increasing amplitudes in the error curve at both ends of the approximation interval, are of course absent, contrary to what usually happens in a least-squares approximation. Author

Subject Categories:

  • Celestial Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE