  Detection of 5 events by the Liquid Scintillation Detector (LSD) on February,
23, 1987 was interpreted in the literature as the detection of neutrinos from
the first stage of the two-stage supernova collapse. We pose rigid constraints
on the properties of the first stage of the collapse, taking into account
neutrino flavour conversion due to the MSW-effect and general properties of
supernova neutrino emission. The constraints depend on the unknown neutrino
mass hierarchy and mixing angle \theta_{13}.
