Proper elements for Earth-crossing asteroids

Proper elements for 987 known near-Earth asteroids (NEAs) have been compute d using a generalized averaging principle, valid also for planet-crossing o rbits. This allows us to assess the maximum and minimum eccentricities and inclinations resulting from secular perturbations, to determine which plane tary orbits can be crossed, and to find the encounter conditions, which can also be used to search for parent bodies of meteor streams. Proper frequen cies for these asteroids have also been computed; it is then possible to dr aw a map of the NEAs affected by the main secular resonances. This paper de scribes the methods used in this computation, discusses the main qualitativ e properties of the results, and announces the availability of the proper e lements online. (C) 2001 Academic Press.