Over 2800 Near-Earth Asteroids (NEAs) have been discovered
to date. On discovery of a NEA, the only physical
parameter that is measured is its brightness at the phase angle
at which it is observed. From this, the absolute visual
magnitude Hv can be estimated by applying a correction to
zero phase angle characterised by an assumed slope parameter,
G (Bowell et al., 1989). The H magnitude alone does not
provide a good constraint on an asteroid’s diameter because
its albedo can lie anywhere in the range 0.02–0.7. Fewer than
70 NEAs have reliably determined albedos and diameters to
date.