The Supernova Rate in Starburst Galaxies

We conducted an optical CCD search for supernovae in a sample of 142 bright (m(B) 16 mag), nearby (z 0:03) starburst galaxies over the period 1988 December to 1991 June, to a limiting R-band magnitude of 18. Five supernovae were found, in all cases outside the host galaxy's nucleus. We determine supernova rates in the extranuclear regions to be 0:7h 2 SNU for type Ia, 0:7h 2 SNU for type Ib/c, and 0:6h 2 SNU for type II, with large uncertainties but upper limits of 2:2h 2 , 2:5h 2 , and 1:7h 2 SNU, respectively. These rates are similar to those measured in \normal" galaxies. We found no evidence for a supernova-induced brightening in any galactic nucleus, and, with a few reasonable assumptions, can place upper limits of 9h 2 , 12h 2 , and 7h 2 SNU on the rates of unobscured supernovae type Ia, Ib/c, and II, respectively, inside the nuclei.