SN1987A neutrino observations at the neutrino detectors Kamiokande II [40], IMB [41], and at Baksan [42]. The energies refer to the secondary positrons from the reaction . In the shaded area, the trigger efficiency is less than 30%. The clocks of the various experiments had unknown relative offsets. Therefore, for each detector spectrum, the time was calibrated such, that the first event was recorded at . In Kamiokande II, the event marked as an open circle is attributed to background (reprinted with permission from [43], Copyright 1999, Annual Reviews).
