When scheduling EME contacts, which of these conditions will generally result in the least path loss?
Why EME path loss follows the inverse square law on both the up and down legs, so total loss scales with the fourth power of distance. Perigee is the closest point of the Moon's elliptical orbit, roughly 356,000 km versus about 407,000 km at apogee, which is worth about 2 dB of extra signal. Operators also favor times when the Moon is high and away from the noisy galactic plane, but path loss itself depends only on range.
Watch out A full Moon is about illumination by the Sun, not distance, and it has nothing to do with radio reflection; in fact a full Moon near the Sun-opposite point can add solar or sky noise concerns but does not change path loss. MUF is an ionospheric parameter and is irrelevant to a signal that must pass through the ionosphere to the Moon.
PERIgee = PROXIMITY. Closest Moon, strongest echo, about 2 dB better than apogee.