Distance modulus ([mu] or DM)
A measure of distance for professional astronomers. The distance
modulus really is the difference of an object's apparent and absolute
magnitudes. The distance in
parsecs can be calculated with equation:
DM = m - M = 5 lg (r / 10 pc) + A
where m is the apparent and M the absolute magnitude,
r is the distance in parsecs, and A
extinction.