Only supernovas within 50k light years will be counted.

Any supernova type counts, including a type Ia supernova.

Regular novas do not count, nor do other exotic events.

The market closing date will extend until a supernova explosion is detected within 50k ly from earth at which point the supernova progenitor will be selected as the answer.

Feel free to add other candidates, but please make sure they are within 50k ly.

If there's no consensus about wether an event is a supernova or not, I will try to wait until the controversy is resolved and may refer to sources such as wikipedia or notable scientific publications