Notes from the Back Row: "An Explosion of Explosions"

"I'm looking for things that go bump, burp, or boom in the sky," says astronomer Shrinivas "Shri" Kulkarni, noting that "there is one supernova somewhere in the universe every second." A supernova is the brilliant new object we see when a star explodes, and if that star happens to go off in the nighttime skies over California, the odds are pretty good he'll find it. In his Watson Lecture given on April 25, 2012, Kulkarni, Caltech's John D. and Catherine T. MacArthur Professor of Astronomy and Planetary Science and the director of the Caltech Optical Observatories, described how Caltech's fully automated Palomar Transient Factory—Kulkarni calls it "Transients 'R' Us"—is revolutionizing how we explore the changing sky.

Supernovae fade into oblivion within days, or at best a few months. Catching them while they're bright is a matter of looking in the right direction at the right time—which is what a vast network of telescopes, many of them in the back yards of dedicated amateur astronomers, are doing right now. But the Transient Factory, says Kulkarni, was the first to create a sort of chain in which a discovery by the dedicated wide-field survey telescope automatically directs a larger telescope to zoom in for a closer look that same night; if the second telescope is intrigued by what it sees, the humans are notified so that even bigger telescopes can be brought to bear. "The hardware is, in fact, the smallest part of the cost," Kulkarni says. "The most expensive component is grayware." Now, with the software pipeline up and running, it's time to "go out and look for weird things," says Kulkarni, whose trophies over the years include the discovery of the first millisecond pulsar and the first brown dwarf. The weird things the Factory is finding will make a nice addition to the collection—watch the talk to get a glimpse of them.

"An Explosion of Explosions" is available for download in HD from Caltech on iTunesU. (Episode 11)