Outer Planets

The corrections for Jupiter, Uranus, and Neptune are entirely different. There are differences in heliocentric longitude that are linear from -2999 to +3000, probably a difference in mean motion, and these are corrected by a simple linear correction term applied to longitude. These corrections (including for Pluto) are optional and are selected by checking the box outer planets under apply correction in the More settings dialog. For Saturn there is no linear difference. There are also differences in heliocentric latitude and distance, but these are not linear and cannot be corrected so easily. Fortunately, the differences in latitude are very small and the differences in distance, while not small absolutely, are sufficiently small in relation to the distance of the planet, as to have virtually no effect on geocentric longitude and latitude.

The geocentric coordinates are also corrected by the corrections applied to the earth although these corrections are quite small because of the great distances of the outer planets. The maximum range of uncorrected and corrected differences AE - DE406 that appear in our comparisons (which may not be complete) for geocentric (G) coordinates to the nearest 0.1 unit is as follows, with differences in longitudes shown in the order in which they occur from -2999 to +3000:

 

Planet

Differences

longitude
(seconds)

latitude
(seconds)

distance
(10-6 AU)

Jupiter

uncorrected
corrected

-5.2 to 1.0
-0.5 to 0.7

-0.3 to 0.8
-0.3 to 0.8

-31.7 to 38.5
-9.3 to 8.0

Saturn

uncorrected
corrected

-1.1 to 0.8
-1.1 to 0.8

-0.6 to 0.4
-0.6 to 0.4

-27.0 to 27.5
-20.6 to 25.0

Uranus

uncorrected
corrected

-1.0 to 4.5
-0.6 to 0.8

-0.6 to 0.8
-0.6 to 0.8

-38.9 to 42.2
-39.4 to 35.0

Neptune

uncorrected
corrected

-1.7 to 7.3
-0.4 to 0.7

-0.3 to 0.8
-0.3 to 0.8

-64.5 to 78.7
-52.1 to 67.3

Pluto

uncorrected
corrected

-27.6 to 78.7
-0.8 to 1.0

-18.3 to 13.4
-0.9 to 0.8

-2363 to 2295
-112.3 to 78.0

 

Alcyone Ephemeris Documentation
(C) 2007 Alcyone Software