A “supernova” is literally a star that blows itself apart. The Crab Nebula is one of the most well known remnant nebulae but still requires binoculars and a dark sky to see. This particular supernova was observed by Chinese, Japanese, and Arabic astronomers, and was the first supernova remnant to be tied to a particular explosion.
There were a couple of observed naked eye supernova recorded just prior to the development of the telescope (Kepler's Star, Tycho's Star) — not that much useful data could have been gleaned before the development of spectroscopy in the 19th century. Still the timing is ironic.
But the science goes on, because our technology allows us to glean very good data from supernovae in galaxies far, far away...but until just recently (2020) we have never seen the explosion happen.
Now we have, and it was not what theoretical folks thought. The expectation was a star slowly growing cold and bloated, and not much happening before the final collapse of the star’s core. It turns out, the first time we get a lot of observations of a star before it blew up it was not quiet at all. In fact, it was the sudden brightening of this far away star (120 million light years!) that got astronomer’s attention and then 4 months later the supernova happened.
I wish I could explain it as well as someone like AKAlib of Skrylax could…
Here is the actual paper