The "distance ranges" that have been added
to the tables represent the orbital "ring" of the major planets defined
by their osculating perihelion and aphelion distances.
Orbit crossings are very sensitive to small errors in the ephemerides, especially for the outermost planets and the Centaurs, whose motion is not well known before the 20th Century. And this is particularly true regarding distances. For my calculations, I have used the complete VSOP87 theory in combination with the numerical integrations of the centaurs. The accuracy is 1 day, assuming that the orbits are exact.
