University of Arizona astronomers are using NASA’s Swift satellite and the Kitt Peak telescope called “Super-LOTIS” to see stars almost as they explode.

Until very recently, astronomers saw supernovae explosions after a lag time of days or weeks. And until very recently, they didn’t see the fast-fading X-ray emission or ultraviolet light that comes with these cosmic blasts.

Astronomers from Goddard Space Flight Center, Penn State University and the UA collaborate in using the new space-based “Swift” telescope. Swift, which is named for a very fast bird, and the UA’s Super-LOTIS are primarily used together to study gamma-ray bursts, the most energetic explosions in the universe. Most gamma-ray bursts last no longer than about ten seconds, so speed is essential in this research.

This rapid-response capability has empowered scientists to study supernovae more quickly than ever before, and, from space, see previously undetected X-ray and ultraviolet emission.

“For many supernovae, we are getting to the scene of the crime to investigate within hours to days, as opposed to the typical delay of days to weeks,” NASA Goddard Space Flight Center scientist Stefan Immler announced at an astronomy meeting in San Francisco yesterday. The team has witnessed more than two dozen supernovae soon after their explosions over the past several months, he said.

“We’re now observing supernovae as quickly as within four hours of their detection,” Steward Observatory’s Peter Milne said. Milne is principal investigator for Super-LOTIS and, along with Philip Pinto and Luc Dessart of Steward Observatory, on the Swift science mission team.

Swift has three telescopes: A gamma-ray telescope to detect the burst, and X-ray and ultraviolet/optical telescopes to provide rapid follow-up observations, all the while broadcasting the burst location to other observatories. For gamma-ray bursts that turn out to be supernovae, Swift actually catches stars as they explode.

“Swift detects a supernova in X-ray and ultraviolet emission,” Milne said. “We put every supernova in the Swift satellite’s observing queue into our (Super-LOTIS) queue to observe it optically.”

The Super-LOTIS telescope (Livermore Optical Transient Imaging System) is a robotic telescope housed in a roll-off-roof dome near the Spacewatch telescopes on Kitt Peak. The experiment is a collaboration of Steward Observatory, Lawrence Livermore National Laboratory, NASA Goddard and Clemson University. In “sky patrol” mode, the small, 0.6-meter (roughly 24-inch) telescope takes about 250 60-second exposures each night. Super-LOTIS began patrolling the sky for gamma-ray bursts and supernovae in October 2005.

The new ability to catch supernovae on the fly in ultraviolet and X-ray wavelengths has given astronomers the first detection of X-rays from a “Type Ia” supernovae – the ‘standard candles’ astronomers use to measure distances in the universe. The detection provides observational evidence to support a theory about their origin. Detection of X-rays from a different supernova has provided proof that “Type II” supernovae emit X-rays that fade within days after the stars blow up.

NASA’s Swift satellite and Super-LOTIS are “proving to be crucial in unraveling the supernova mystery as well the gamma-ray bursts,” said Swift Principal Investigator Neil Gehrels of NASA Goddard. (Gehrels’ father, Tom Gehrels, and brother, George Gehrels, are members of the UA faculty.)

Related Web sites

http://slotis.kpno.noao.edu/LOTIS/

http://www.nasa.gov/centers/goddard/news/topstory/2006/supernova_mugshot.html