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Redshift-magnitude Relation

(Magnitude-redshift relation)
(how apparent magnitude depends on redshift)

The Redshift-Magnitude Relation (or Magnitude-redshift Relation) is a function of Redshift (or distance) that yields (effectively) the Distance Modulus associated with that redshift: the difference between Apparent Magnitude and Absolute Magnitude. This was of great interest when the expansion of the universe was first being proposed.

It is also of current interest: like the Redshift-angular Size Relation, it is straight-forward given some simplifying approximations: in this case, constant. However, at Cosmological distances, various models as well as observation reveal it is not so simple, and observation can be used to select and tweak models.