  Numerous estimates of upper bounds on the (anti)neutrino rest mass have been
published based on the SN1987A observations.
  Here, we use a nonkinematic (thermal) time extent to provide a rest mass
estimate of a few eV (as mc^2 mass), if not zero. In the solution, we find that
a typical upper bound formula for the mass implies that this thermal extent was
attributable to about 10% of the particle energy measured on Earth. The present
approach yields an expected value for the mass, given any theoretical or model
dependent estimate of the fraction of the detected neutrino energy attributable
to the supernova temperature.
