In the galsat-type ephemerides, the Jovicentric Earth-equatorial coordinates of the Galilean satellites are computed as a function of 50 "galsat'' parameters (Lieske 1977). The definitions of the basic parameters upon which the theory depends are given in Tables 2 (click here) and 3 (click here). It is seen that they are a combination of physical parameters and orbital elements.
In the E5 ephemerides, we employed the satellite masses (
) and Jupiter pole which were determined by Campbell
& Synnott (1985) from their analysis of the Voyager data. The Jupiter pole is a function
of the longitude of the origin of the coordinates 
[theory parameter
], and the inclination 
of Jupiter's equator to Jupiter's orbit
[theory parameter 
], with some dependence upon the Jupiter
orbital inclination to the ecliptic [theory parameter 
],
Jupiter's node 
[theory parameter 
], and the obliquity
of the ecliptic [theory parameter 
]. The mass
of the Jupiter system was that of JPL ephemeris DE140 (Standish & Folkner
1995) Sun/Jupiter-system = 1047.3486. Ephemerides E3 and E4 employed
Jupiter system masses which are consistent with JPL ephemeris DE125 (Standish
1985), Sun/Jupiter-system = 1047.349. The Jupiter pole employed was
and 
at the theory epoch JED
2443000.5 and in the B1950 frame.
The rate of [theory parameter ] models the
secular motion of Jupiter's pole from the theory epoch. Jupiter's oblateness
parameters J2 and J4 were also taken from the Campbell & Synnott
analysis. They correspond to theory parameters 
and
in Table 2 (click here).
Over the years different tables of 
have been used for the
calculation of Ephemeris Time (barycentric dynamical time TDB) minus Universal
Time. The appropriate table of values depends upon what model
of the Moon's
tidal acceleration one adopts. The Earth's Moon was most often used to
determine values of prior to 1955 because of its rapid motion.
The derived values of
effectively depend upon a partitioning into portions due to lunar tidal effects
versus real changes in . It essentially depends upon the parameter employed
to describe the lunar tidal acceleration 
. The classical
determination of 
arcsec/cy2 by Spencer Jones (1939)
was employed for the E1 and E2 (Lieske 1980) ephemerides by means of the Brouwer
(1952) and Martin (1969) values of , which were on the
Spencer Jones system.
The Morrison and Ward (1975) value of 
arcsec/cy2
was used for E3, E4 and E5. Tables of given by Stephenson & Morrison
(1984) can be adjusted for any by the technique noted in Lieske
(1987) for times prior to 1955.5 by computing
where 
is measured in centuries from the 1955.5 epoch of Morrison (1980).
The theory parameters of E1 and E2 are consistent with the Spencer-Jones value
of , while those for E3 through E5 are consistent with that of
Morrison and Ward.
Table 2: Definition of theory parameters
Table 3: Definition of theory parameters 