I am indebted with J. Masdemont for his version of the code developed in Gómez et al. (1985; 1987; 1991; 1993) to work with the JPL ephemeris. I also want to acknowledge interesting discussions with C. Simó, and the comments of S. Haberman on a preliminary version of the paper. This research has been supported by the Spanish grant DGICYT PB94-0215 and the Catalan grant CIRIT 1998S0GR-00042. The numerical simulations have been carried out on Hidra, the Beowulf cluster of the UB-UPC Dynamical Systems Group (http://www.maia.ub.es/dsg/hidra/ ).
© European Southern Observatory (ESO) 2000
Online publication: December 15, 2000