2011-01-14 (NASA Press Release)

NASA Satellites Find High-Energy Surprises in 'Constant' Crab Nebula

The combined data from several NASA satellites has astonished astronomers by revealing unexpected changes in X-ray emission from the Crab Nebula, once thought to be the steadiest high-energy source in the sky.

"For 40 years, most astronomers regarded the Crab as a standard candle," said Colleen Wilson-Hodge, an astrophysicist at NASA's Marshall Space Flight Center in Huntsville, Ala., who presented the findings today at the American Astronomical Society meeting in Seattle. "Now, for the first time, we're clearly seeing how much our candle flickers."

X-ray data from NASA's Fermi, RXTE, and Swift satellites and the European Space Agency's International Gamma-Ray Astrophysics Laboratory (INTEGRAL) confirm that the Crab Nebula's output has declined about 7 percent in two years at energies from 15,000 to 50,000 electron volts. They also show that the Crab has brightened or faded by as much as 3.5 percent a year since 1999. Fermi's Large Area Telescope (LAT) has detected powerful gamma-ray flares (magenta lines) as well.

2011-01-10 (MPE Press Release)

Space telescope catches antimatter from terrestrial thunderstorms

Normally astronomers look deep into space, but in the latest finding from the NASA Fermi Gamma-ray Space Telescope presented on Monday, Jan. 10, during a news briefing at the American Astronomical Society meeting, they detected an antimatter signal from Earth. Created in energetic processes above thunderstorms, when such an antimatter beam strikes the spacecraft, it actually becomes a source of the gamma-ray light it was designed to observe. Scientists at the Max Planck Institute for Extraterrestrial Physics (MPE) were responsible for the development of the detectors and the power supplies of the Fermi Gamma-ray Burst Monitor (GBM), which led to this discovery, and contributed to the calibration and data analysis for this particular result.

 

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While Fermi flew over Egypt, the GBM intercepted a particle beam from a terrestrial gamma-ray flash (TGF) that occurred in a thunderstorm below its horizon.
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