Neutrino Properties and Supernova SN1987a

In the two years since the last fourth family meeting considerable improvement in direct ν mass and mixing measurements has been achieved. The number of ν families is limited by colliders and e⁺e⁻ννγ experiments and will soon be determined by measurement of the Z width. Here I will focus on how the single dramatic event of SN1987a indicated how limits on ν properties can be deduced from the observed ν signals. We briefly review these signals in the first section below, and explain how they could be used for the above purpose.