Supernova are powerful enough that even a star in a different solar system going nova can kill you, if it's a "nearby" system. But I believe there aren't any stars close enough that would go supernova any time soon.
Perhaps the story could have Cylons in it, but here they're allies with the humans, but after the supernova, some religious leader convinces most of them that their god wants them to destroy the humans.
I think, ball park, a SN 500 light years out is considered safe e.g. Betelgeuse. Our Milky Way galaxy is thought to be roughly 100,000 light years in diameter so we should be safe from all but those within about a hundredth of the radius of our galaxy from us.
space is big ...