Near-Earth asteroids are divided into groups (Atira, Aten, Apollo and Amor) according to their perihelion distance (q), aphelion distance (Q) and their semi-major axes (a).
Since the taxonomic class of most NEAs is unknown, we simply use an assumed mean albedo of 14% to estimate all NEA sizes. With this assumption, a one kilometer spherical NEA corresponds to an H value of 17.75.
