[1] Max Planck Inst Aeron, D-37191 Katlenburg Lindau, Germany
[2] Observ Paris, F-92195 Meudon, France
[3] Bur Longitudes, F-75014 Paris, France
[4] Planetarium St Etienne, F-42100 St Etienne, France
[5] European Space Agcy, Dept Space Sci, NL-2200 AG Noordwijk, Netherlands