The Environments of Supernovae in Archival Hubble Space Telescope Images

We have examined the immediate environments of several supernovae using archival prerefurbishment Hubble Space Telescope images to search for clues to the nature of the progenitor stars. For the Type II supernova 1968L in M83 the colors of nearby star clusters indicate ages of <~ 6-7 x 10^6^ yr, implying an initial mass of ~> 25-30 M_sun_ for the progenitor, if it formed coevally with the clusters. This limit is higher than expected for a typical Type II progenitor, and may indicate that the supernova progenitor formed earlier than the nearby clusters. Images of M 51 obtained prior to the explosion of the Type Ic SN 19941 are used to derive an upper limit to the absolute magnitude of the progenitor star of M_v_ > -7.3+/-0.7 mag. This limit is unfortunately not sufficiently restrictive to constrain models of Type Ic supernovae. We also discuss images containing the sites of supernovae 1991N (Type Ic), 1992bd (Type II), and several Type Ia supernovae. As higher-quality post-refurbishment data become available in the archive, we expect substantial improvement in our understanding of individual supernova environments.