Estimating Distances To Cepheids & Type 1a Supernovae

To estimate distances to Cepheids and type 1a supernovae, measure apparent magnitudes and use the following formula where m is the apparent magnitude and M is the absolute magnitude:

10^{(m - M + 5) / 5} pc

M = -19.3 for type 1a supernovae.  For a Cepheid with an absolute magnitude of -5.65 and an apparent magnitude of 23:

10^{(23 - (-5.65) + 5) / 5} = 5,400,000 pc.  

For a type 1a supernova with an apparent magnitude of 14:

10^{(14 - (-19.3) + 5) / 5} = 46,000,000 pc.