THE space telescope Swift has caught its first glimpse of the fading glow of a gamma-ray burst. Swift should help probe the mysteries of these explosions, which could signal the birth of black holes or collisions between them.
Gamma-ray bursts are the largest releases of energy in the universe. Each lasts up to a few minutes, and often an X-ray and optical afterglow persists for hours or days. But monitoring the afterglow is difficult because until now it has taken hours to get telescopes into action.
Swift is meant to remedy that. Launched in November, it carries a gamma-ray detector to spot the explosion, and then automatically points an X-ray telescope towards it. The afterglow observations will reveal the explosion energies and temperatures, and help pin down what causes the bursts.
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In a trial run in mid-December, Swift鈥檚 X-ray telescope snapped an intriguing image of Cassiopeia A (pictured), a supernova remnant in the Milky Way that would first have been visible from Earth three centuries ago. 鈥淚t tells us that the instrument is working very well,鈥� says David Burrows of Pennsylvania State University, an astronomer on the Swift team. On 23 December Swift bagged its first gamma-ray burst afterglow. 鈥淪oon we鈥檒l be looking at these bursts within a minute or two after they go off, and we really don鈥檛 know exactly what we鈥檒l see,鈥� Burrows says.
