While you were sleeping, a new supernova appeared in the sky

The bright ball at the right hand end of the Cigar Galaxy is, probably, what it looks like when an old, cold, dense husk of a star (aka a "white dwarf") explodes 12 million light years away. It may not look as impressive as you'd imagine, but astrophysicists were extremely excited when this likely supernova appeared in the sky last night. The big question now: Is it the result of one white dwarf going boom, or two white dwarfs crashing into each other?