NASA Swift mission turns on and sees a blast of bursts

Dolores Beasley
Headquarters, Washington January 5, 2005
(Phone: 202/358-1753)

Nancy Neal-Jones
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-0039)

RELEASE: 05-005

NASA SWIFT MISSION TURNS ON AND SEES A BLAST OF BURSTS

The NASA-led Swift mission opened its doors to a flurry of gamma
ray burst action.

Scientists were still calibrating the main instrument, the Burst Alert
Telescope (BAT), when the first burst appeared on December 17. Three
bursts on December 19, and one on December 20, followed.

Swift's primary goal is to unravel the mystery of gamma ray bursts. The
bursts are random and fleeting explosions, second only to the Big Bang
in total energy output. Gamma rays are a type of light millions of
times more energetic than light human eyes can detect. Gamma ray bursts
last only from a few milliseconds to about one minute. Each burst
likely signals the birth of a black hole.

"The optimists among us were hoping to detect two bursts a week, not
three in one day just after turning the telescope on," said Dr. Scott
Barthelmy, the BAT lead scientist at NASA's Goddard Space Flight
Center, Greenbelt, Md. "Maybe we got lucky, or maybe we've
underestimated the true rate of these bursts. Only time will tell," he
added.

Once the BAT, that covers about one-seventh of the sky at any time,
detects a gamma ray burst, it quickly relays a location to the ground.
Within about one minute, the satellite automatically turns toward the
burst. The move brings the burst within view of Swift's two other
telescopes: the X-ray Telescope (XRT) and the Ultraviolet/Optical
Telescope (UVOT).

Once all three instruments are turned on and calibrated, Swift will get
down to the business of analyzing gamma ray bursts. "The universe kept
up its side of the bargain, and we kept up ours," said Dr. Neil
Gehrels, Swift's Principal Investigator at Goddard. "This is going to
be an exciting mission," he said.

The Swift team tested the BAT by observing Cygnus X-1, a well-known
bright source that produces gamma rays in our galaxy. It is thought to
be a black hole in orbit around a star. The team called this BAT's
"first light."

The BAT is the most sensitive gamma ray detector ever flown. The BAT
employs a novel technology to image and locate gamma ray bursts. Unlike
visible light, gamma rays pass right through telescope mirrors and
cannot be reflected onto a detector. The BAT uses a technique called
"coded aperture mask" to create a gamma ray shadow on its detectors.
The mask contains 52,000 randomly placed lead tiles that block some
gamma rays from reaching the detectors. With each burst, some detectors
light up while others remain dark, shaded by the lead tiles. The angle
of the shadow points back to the gamma ray burst.

"The BAT coded aperture mask is about the size of a pool table, the
largest and most intricate ever fabricated," said Ed Fenimore of Los
Alamos National Laboratory, N.M. Los Alamos created the BAT software.
"BAT can accurately pinpoint a burst within seconds and detect bursts
five times fainter than previous instruments," he added.

Swift, a medium-class explorer mission managed by Goddard, was launched
from Cape Canaveral on November 20, 2004. The mission is in
participation with the Italian Space Agency and the Particle Physics
and Astronomy Research Council in the United Kingdom.

Swift was built at Goddard in collaboration with General Dynamics,
Ariz.; Penn State University, College Station, Pa.; Sonoma State
University, Rohnert Park, Calif.; Los Alamos; Mullard Space Science
Laboratory, Surrey, England; the University of Leicester, England; the
Brera Observatory, Milan, Italy; and ASI Science Data Center, Rome.

Images of the BAT's "first light" and Swift's first bursts are on the
Internet at:

http://www.nasa.gov/vision/universe/...irst_light.htm
l

For more information about NASA and agency programs on the Internet,
visit:

http://www.nasa.gov


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Jacques :-)

www.spacepatches.info