When really interesting things happen in deep space, you can bet there will be a flurry of e-mails zipping around Earth.
That's how researchers make sure the best telescope possible captures images of short-lived events like an exploding star called SN 1999-em, first observed October 29.
An automated supernova search project, led by Alex Fillipenko of the University of California, spotted a good candidate on that Friday in October.
Astronomers around the world quickly were notified in what has become standard practice for supernova searchers.
Among those notified was Bob Kirshner at the Harvard-Smithsonian Center for Astrophysics.
Kirshner e-mailed Harvey Tananbaum, director of the Chandra X-ray Center, a little before 11 p.m. on Saturday night.
The Chandra team changed the telescope's observation schedule, and by Monday morning the observatory was pointed at the supernova, observing it for about nine hours.
The result is a rare glimpse of X-rays from the early phases of a supernova, one of the most violent cosmic events.
Although more than a thousand supernovas have been observed by optical astronomers, the early X-ray glow from the explosions has been detected in less than a dozen cases, researchers say.
When combined with simultaneous observations by radio and optical telescopes, the X-ray observations tell about the thickness of the shell that was blown off, its density, its speed, and how much material was shed by the star before it exploded.
Optical observations showed that SN 1999-em was produced by the collapse of the core of a star ten or more times as massive as the sun.
The intense heat generated in the collapse produces a cataclysmic rebound that sends debris flying outward at speeds in excess of 20 million m.p.h. (32 million kilometers per hour).
The debris crashes into matter shed by the former star before the explosion. Shock waves from the collision heat expanding debris to 3 million degrees, producing the X-rays detected by Chandra.
The combined observations indicate that SN 1999-em shed a relatively small amount of matter before it exploded, compared to other supernovas observed in X-rays, said Roger Chevalier of University of Virginia.
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