The Luminosity of Supernovae of Type Ia. I. Apparent Magnitudes at Maximum Light

All published UBV and m pg m pv photometry is used to determine maximum magnitudes for 31 supernovae of Type Ia (SN Ia). The main results of this work are summarized in a list of maximum magnitudes, and an estimate of their precision, for all objects which have been designated SN Ia on the basis of their spectra, and for a few supernovae in elliptical galaxies which were assumed to be of Type Ia.