Hi Robin.
Thanks for all that, some more readings and videos.
“These different types of event have characteristic spectral features and are very different from what the spectrum would have been before the explosion.”
It would be someone’s lucky day had they just recently randomly acquired data on a random star before and then heard of an event, then went to analyse it again on the same kit. But then, there would probably be no reason to have targeted though, unless there had been suggestions of activity.
Derek