SN1987A

This supernova made big news because it was the first (and so far only) one to be detected in signals other than light. Several neutrino detectors spotted it too--and they spotted it first. Current models of supernovae hold that the neutrino burst comes first, and drives the rest of the explosion--not that these energy ranges of neutrinos interact very strongly, but that there are so many of them and the star is so dense that the pressure makes the star explode.

Christian Spiering wrote a book about neutrino astronomy (currently only in German). In his description of SN1987A and his book in a newsletter he points out that the detection was a near-run thing. "In 1987, there were five detectors in the world that could be used for the detection of a short neutrino burst:"

1. Kamiokande "was switched off for a routine calibration two minutes after the arrival of the neutrinos"
2. IMB's magnetic tape was almost full and wouldn't have recorded it "unless a proud graduate student hadn’t wished to show his girlfriend the facility on Sunday evening. He drove down into the mine with her, noticed that the tape was nearly full, and exchanged it for a new one"
3. Atryomovsk: it was Soviet Army day, which was effectively a holiday, and the detector was off
4. Baksan: the director made sure it kept running despite the "holiday"
5. Liquid Scintillation Detector: nothing went wrong, except maybe the detection itself, which is disputed to this day (they saw something earlier than the rest, with a smaller detector.

Uptime is important.