Abstract

The usefulness of type Ia supernovae as distance indicators is a matter of current study and discussion. The available data suggest that the intrinsic dispersion in the absolute B magnitudes of SNe Ia at maximum light is less than 0.4 mag. Hence, SNe Ia offer considerable potential for cosmological studies out to redshifts of z = 0.1 or greater. In this paper we make use of the best spectra available for type Ia supernovae in order to calculate the effect of the redshift on the observed B and V magnitudes. We present K terms in the redshift range z = 0.005-0.50 from a collection of spectra of SNe 1990N, 1991T, and 1992A covering from day -14 to day +76, counted from the time of maximum light in the blue band. Our calculations enable us to interpolate K terms for SNe Ia at maximum light, which should prove useful to study the Hubble diagram for these objects.