The long term goal of this research is to understand supernova explosions and use that knowledge to determine the distances of other galaxies. These distances are basic to our efforts to understand the origin of the universe and determine its age. The approach is based on observations followed by close comparison of the data to theoretical models. As the research proceeds, such questions as the rate of supernovae in our galaxy and other galaxies, the types of stars which become supernovae, the effects of these explosions on the interstellar gas, the role of supernovae in manufacturing heavy elements, the energy output of supernovae and the properties of various types of supernovae will be addressed. This work has been underway for more than a decade and will continue under this grant.