UPDATED LIMITS ON THE ELECTRON NEUTRINO MASS AND LARGE-ANGLE OSCILLATIONS FROM SN1987A

We supplement Maximum Likelihood methods with a Monte-Carlo simulation to re-investigate the SN1987A neutrino burst detection by the IMB and Kamiokande experiments. The detector simulations include background i n the the latter and ''dead-time'' in the former. We consider simple n eutrinosphere cooling models, explored previously in the literature, t o explore the case for or against neutrino vacuum mixing and massive n eutrinos. In the former case, involving kinematically irrelevant masse s, we find that the full range of vacuum mixing angles, 0 less than or equal to sin(2) 2 theta(V) less than or equal to 1, is permitted, and the Maximum Likelihood mixing angle is sin(2) 2 theta(V) = 0.45. In t he latter case we find that the inclusion of ''dead-time'' reduces pre vious m(upsilon e), upper bounds by 10%, and supplementing the Maximum Likelihood analysis with a Monte-Carlo goodness-of-fit test results i n a further 15% reduction in the m(upsilon e) upper Limit. Our 95% C.L . upper limit for m(upsilon e) is 19.6 eV, while the best fit value is similar to 0 eV.