Originally Posted by Drone
They said that it was seen in 1054 and lasted for two years. What we see now is all the radiation that left after the explosion.
So I think actual
explosion happened 6500 (distance) + 1054 (when it was observed) = 7554 years ago
I might be wrong
If the distance to the nebula is 6500 ly, then the blast actually took place 6500+958=7458 years ago realtime. And it was observed on Earth in 1054 (958 years ago).