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

January 10, 2013
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. (Image credit: NASA's Goddard Space Flight Center)