Atens: Importance among Near-Earth Asteroids and search strategies

The class of Near-Earth Asteroids known as Atens are very important search targets for two reasons: first, recent studies have shown that they have the highest intrinsic frequency of close encounters with the Earth, and second, they are probably undersampled in the known NEA population, as searches have always concentrated toward the opposition region. In order to remove this bias, we outline a few search strategies to increase their discovery rate with the available equipment, before an all-sky survey up to magnitude 22 is implemented (the Spaceguard Survey). Searches should concentrate on two regions located between 50° and 120° of elongation from the Sun. The Campo Imperatore Near-Earth Object Survey (CINEOS) will be the first specific search program to implement such a strategy.