SIMBAD references

We have compiled a sample of 667 spiral galaxies selected from the Second Reference Catalogue of Bright Galaxies (RC2) (de Vaucouleurs et al. 1976). 169 supernovae (SNe) were discovered up to 31 Dec., 1992 in the entire galaxy sample, and two or more SNe have been found in 30 galaxies. We have taken into account several selection effects,i.e. the effects of Hubble types, luminosity, inclination and distance of the galaxies, to check whether the frequency distribution of SNe follow a Poisson distribution, and whether the deviation from Poisson distribution are due to `burst of star formation' as proposed by Ritcher & Rosa (1988, hereafter RR). It is found that after considering the effect of luminosity and distance of the galaxies, more homogeneous galaxy samples with the same Hubble types and inclination range have significantly smaller deviation from a Poisson distribution. Some of the subsamples have acceptable Poisson distributions. The distinction between the supernova(SN) frequency of `SN fast producer' galaxies and normal galaxies is found to be 4∼6 times, which is significantly smaller than that proposed by RR (70 times!), and can be regarded as fluctuations of SN frequencies of different galaxies. We suggest that there is no need to consider some of the galaxies as `fast producers of SNe' and that the deviation from Poisson distribution can be interpreted as joint effects of star formation, Hubble types, luminosity,inclination and distance of the galaxies. We have also done an analysis of the radial distribution of SNe in their parent galaxies. There is an indication that multiple SNe are located farther from the nuclei of their parent galaxies, which is a further evidence to reject the existence of `fast producers of SNe'.