[joelshep]

In our galaxy, or anywhere? In our galaxy, potentially 1-3 times per century but there are reasons (besides probabilities being what they are) that we humans haven't actually observed one in some time: https://phys.org/news/2021-01-milky-supernovae-millennium.ht... . Across the universe, the estimate is one star goes supernova every ten seconds. Actually observed: about 1-2 per week. There are systems and amateurs who regularly scan the night sky looking for evidence of supernovas and other "transient" objects. And a central database where they are reported: https://www.wis-tns.org/ . Get an account and sign up for notifications, and you'll get several a week reporting things that probably went boom far, far, far away. Looking to place bets? Betelgeuse is considered a strong contender for the next supernova progenitor that we humans will see with our naked eyes, probably even during daylight hours.