Close encounters of Near Earth Objects with large asteroids
  Close encounters of Near Earth Objects (NEOs) with large asteroids are a possible source of systematic errors in trajectory propagations and asteroid mitigation. It is, thus, necessary to identify those large asteroids that have to be considered as perturbers in NEO orbit modeling. Using the Standard Dynamical Model we searched for encounters between the 1649 numbered Near Earth Asteroids (NEAs) and 2191 large asteroids having sizes greater than 20 km. In- vestigating the 21st century A.D. we have found 791 close encounters with 195 different large asteroids that lead to a substantial scattering of NEOs. 
Anatoliy Ivantsov, Siegfried Eggl, Daniel Hestroffer, William Thuillot   and Pini Gurfil
astro-ph.EP