Identified by scientists at Los Alamos National Laboratory about 30 years ago, gamma-ray bursts are believed to signal the births of black holes and hold clues to how our universe was formed.

Still, little is known about the massive, short-lived explosions including why they happen.

But scientists at a telescope at the Fred L. Whipple Observatory at Mount Hopkins, Ariz., observing one gamma-ray burst, reported spotting something completely new on Dec. 19 — an infrared flash. In the following days, the W.M. Keck Observatory atop the summit of the Mauna Kea volcano on the Big Island continued to keep watch as the energy of the blast faded.

The discovery of the flash is reported in tomorrow's issue of the journal "Nature."

Gamma-rays are a high-energy form of light, while infrared light are a relatively lower-energy form of light. Neither is visible to the naked eye.

While infrared light has been seen following a burst before, it was believed to have been caused by interactions with material around the explosion site.

The possibility of an infrared flash being part of the burst hadn't really been discussed by theorists before, so it came as a surprise, said Joshua Bloom, astronomy professor at the University of California at Berkeley and senior author of the article.

"It's sort of like finding out an old friend is a little bit more complex," Bloom said.

In their analysis of the event, the authors of the article concluded that the flash was the result of the process that creates the burst itself.

What attracts scientists to the gamma-ray burst is the prodigious amount of energy they put out within a tiny fraction of a second, said Frederic Chaffee, director of the Keck Observatory.

Engulfing the sky about once each day, gamma-ray bursts are more powerful than everything else in the universe combined. Within moments the blast is gone without a soul on the ground ever knowing it even happened — except a cadre of astronomers behind powerful telescopes.

The bursts are believed to be the result of the collision between or collapse of neutron stars, super-dense, dead stars.

But astronomers are still in the early phases of understanding the physics of the phenomenon and finding an application for those discoveries might not appear for decades, Chaffee said.