  Blue Supernovae of Type Ia (SNe Ia) have become the most important objects in
cosmology being of exceptionally uniform luminosity. Used as relative distance
indicators they map deviations from pure Hubble flow and determine the
cosmological constant Lambda. Once their absolute magnitude is determined they
provide the best estimate of the large-scale value of the Hubble constant H_0.
An HST project is reviewed where Cepheid distances are used for the luminosity
calibration of SNe Ia. The mean luminosity of 8 SNe Ia is M_B(max)= -19.47 +/-
0.07, M_V(max)= -19.48 +/- 0.07, corresponding -- after small corrections for
second parameters -- to H_0(cosmic)= 59 +/- 5.
