Observations of the 1968 Type II Supernova in NGC 5236

Abstract

NGC 5236 is an Sc galaxy (Sandage, 1961) viewed almost face-on and is known to have produced four supernovae (e.g., Tammann, 1970). Two of these were of unknown type while that of 1923 shows a light curve (Lampland, 1936) suggestive of type II but apparently underluminous; the light curve is discussed by de Vaucouleurs elsewhere in these proceedings. The 1968 supernova was observed photometrically with the Radcliffe 1.88 m reflector following its visual discovery on July 16 by Pretoria amateur J. C. Bennett in the course of his search for comets. It is found to be typical of type II, although its site, superimposed on the nucleus of the galaxy, is unusual and in marked contrast to the three previous events which occurred far out in the spiral arm structure (Karpowicz and Rudnicki, 1968).

The work summarized here was carried out jointly by P.J. Andrews of the Radcliffe Observatory, Pretoria, and theauthor. A full discussion of the observations, with diagrams, is presented elsewhere (Wood and Andrews, 1974).