The Detection of a SN IIn in Optical Follow-up Observations of IceCube Neutrino Events
M. G. Aartsen et al 2015 ApJ 811 52
Optical follow-up of a neutrino alert from IceCube found a spatially-coincident, unusual type IIn supernova — but it exploded 158 days before the neutrino detection, so it wasn’t the neutrinos’ source.