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Kamiokande, associated with Masatoshi Koshiba, was an underground water Cherenkov detector viewed by photomultipliers. Improved water purity and reduced background enabled solar neutrino observations. A concentration of reconstructed recoil directions toward the Sun distinguished a source signal above an approximately direction-independent background.^[ref]

For solar neutrinos, Electron elastic scattering supplies a directional recoil, with different cross sections for active neutrino flavors. Neither the Homestake experiment deficit nor the SN 1987A neutrino burst alone established neutrino oscillation; later evidence compared complementary channels and propagation effects.^[ref]

Neutrino astronomy infers properties of astronomical sources from detected neutrino reactions. Solar neutrino detection probes ongoing stellar nuclear fusion; the SN 1987A neutrino burst probes a brief episode of core-collapse supernova evolution. A detector observes reaction products, so source inference depends on cross sections, neutrino flavor, thresholds and detection efficiency.

SN 1987A supplied a prompt terrestrial record of neutrino emission from a core-collapse supernova through its SN 1987A neutrino burst.^[ref]