The Asiago Supernova Catalog is used to carry out a comparative study of supernova absolute-magnitude distributions. An overview of the absolute magnitudes of the supernovae in the current observational sample is presented, and the evidence for subluminous and overluminous events is examined. The fraction of supernovae that are underluminous (M B > −15) appears to be higher (perhaps much higher) than one fifth but it remains very uncertain. The fraction that are overluminous (M B < −20) is lower (probably much lower) than 0.01. The absolute-magnitude distributions for each supernova type, restricted to events within 1 Gpc, are compared. Although these distributions are affected by observational bias in favor of the more luminous events, they are useful for comparative studies. We find mean absolute blue magnitudes (for H 0 = 60) of −19.46 for normal Type Ia supernovae (SNe Ia), −18.04 for SNe Ibc, −17.61 and −20.26 for normal and bright SNe Ibc considered separately, −18.03 for SNe II-L, −17.56 and −19.27 for normal and bright SNe II-L considered separately, −17.00 for SNe II-P, and −19.15 for SNe IIn.

The absolute visual magnitudes of three Type IIb, 11 Type Ib, and 13 Type Ic supernovae (collectively known as stripped-envelope supernovae) are studied by collecting data on the apparent magnitude, distance, and interstellar extinction of each event. Weighted and unweighted mean absolute magnitudes of the combined sample, as well as various subsets of the sample, are reported. The limited sample size and the considerable uncertainties, especially those associated with extinction in the host galaxies, prevent firm conclusions regarding differences between the absolute magnitudes of supernovae of Types Ib and Ic, and regarding the existence of separate groups of overluminous and normal-luminosity stripped-envelope supernovae. The spectroscopic characteristics of the events of the sample are considered. Three of the four overluminous events are known to have had unusual spectra. Most but not all of the normal-luminosity events have had typical spectra. The light curves of stripped-envelope supernovae are collected and compared. Because SN 1994I in M51 was very well observed, it often is regarded as the prototypical Type Ic supernova, but it has the fastest light curve in the sample. Light curves are modeled by means of a simple analytical technique that, combined with a constraint on E/M from spectroscopy, yields internally consistent values of ejected mass, kinetic energy, and nickel mass.

The absolute-magnitude distributions of seven supernova types are presented. The data used here were primarily taken from the Asiago Supernova Catalogue, but were supplemented with additional data. We accounted for both foreground and host-galaxy extinction. A bootstrap method is used to correct the samples for Malmquist bias. Separately, we generate volumelimited samples, restricted to events within 100 Mpc. We find that the superluminous events (M B < −21) make up only about 0.1% of all supernovae in the bias-corrected sample. The subluminous events (M B > −15) make up about 3%. The normal Ia distribution was the brightest with a mean absolute blue magnitude of −19.25. The IIP distribution was the dimmest at −16.75.

ABSTRACT. Seventy-eight photographic spectra of 18 bright supernovae that were obtained by various observers at the Lick Observatory between 1937 and 1971 are presented and brieÑy discussed. Microphotometer transmission tracings of the photographic plates have been digitized and plotted on a common scale with a linear wavelength axis. The spectra were prismatic, with a nonlinear dispersion, in their original form. These spectra are useful for classiÐcation purposes and for comparative studies of the blueshifts of absorption features.