A while back I read about the super Kamiokande detector detected a large neutrino flux and then several hours later a supernova was seen. Anyone know of this with sources? I don't recall the source at the moment.



This website confirms what you said about the neutrinos from the 1987 supernova arriving before the light from the supernova. It doesn't specifically say which detectors detected the neutrinos.

The reason the neutrinos reached earth before the light is not because the neutrinos were travelling faster than light but because they were travelling about as fast as light but were able to escape the star before the shock waves from the supernova explosion (and the subsequent release of light) reached the surface of the star, because neutrinos are able to pass through matter basically unimpeded but the shock waves and photons were interacting with the matter of the star all the way out.

It is worth noting though that the scientists working at Kamiokande didn't look for the neutrinos from before the supernova until the actual supernova was discovered from its electromagnetic emission; thus, although the neutrinos came before the light, nobody noticed until after the fact.

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    $\begingroup$ But now, as far I know, there is a big, global alarm system, even the gravitational wave observatories will be part of it. If a next supernova would happen, the whole Earth would watch only it in seconds. $\endgroup$ – peterh - Reinstate Monica Aug 10 '17 at 18:52
  • $\begingroup$ @peterh, yes, SNEWS (Supernova Early Warning System) is the big global alarm system consisting of (as of two years ago) four neutrino detectors. Perhaps LIGO and other neutrino observatories have been added as well. $\endgroup$ – NeutronStar Aug 10 '17 at 19:25
  • $\begingroup$ And the big (photon) telescopes aren't part of it?? I think, how a supernova behaves in its first seconds in the visible light, could be a very important information. $\endgroup$ – peterh - Reinstate Monica Aug 10 '17 at 19:57
  • $\begingroup$ @peterh, SNEWS is the early warning system that then alerts observers that a supernova is about to become visible. Those observers can then point the optical telescopes at the supernova. The optical telescopes aren't a part of the early warning system; they're the beneficiaries of it. $\endgroup$ – NeutronStar Aug 10 '17 at 21:51

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