Compact ephemerides for the major satellites of Saturn
      D.B. Taylor and B.D. Yallop
    (Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 OEZ,
       U.K. )


Abstract

  The satellite section of the Astronomical Almanac is to be printed
in a more compact form using the method of Chapront and Vu (1984) to
represent the differential equatorial coordinates. This method makes
use of the quasi-periodic character of the orbit by using as basis
functions both secular and periodic terms. This form of representation
of ephemerides has become well established in the annual publications
of the Bureau des Longitudes "Ephemerides of the satellites of Mars,
Jupiter, Saturn and Uranus".
  
  The mixed functions approach and the Chebyschev series approximation
are used to represent compactly the differential equatorial coordinates
of the eight major satellites of Saturn using theories recently devel-
oped at the Royal Greenwich Observatory and the different methods are
compared. Results agree with Arlot, Chapront, Ruatti and Vu (1986)
that for the same number of terms the mixed functions method gives
the same precision as the Chebyshev method, but over a much longer
time interval. It is intended to develop compact ephemerides for the
major satellite systems of Mars, Jupiter, Uranus and Neptune.