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X-ray telescope will provide sharpest images.

Performing beyond expectations, the high-resolution mirrors for NASA's most powerful orbiting X-ray telescope successfully have completed initial testing at Marshall Space Flight Center's X-ray Calibration Facility in Huntsville, Ala. "We have the first ground test images ever generated by the telescope's mirror assembly, and they are as good as -- or better than -- expected," notes Martin Weisskopf, chief scientist for NASA's Advanced X-ray Astrophysics Facility (AXAF).

The mirror assembly, four pairs of precisely shaped and aligned cylindrical mirrors, will form the heart of NASA's third great observatory. The telescope produces an image by directing incoming X-rays to detectors at a focal point some 30 feet beyond the instrument's mirrors. The greater the percentage of X-rays brought to focus and the smaller the size of the focal spot, the sharper the image.

Tests show that, in orbit, the mirror assembly will be able to focus approximately 70% of X-rays from a source to a spot less than one-half an arc second in radius. An arc second is an extremely small angular measure, one-3,600th of a degree. The telescope's resolution is equivalent to being able to read the text of a newspaper from half a mile away. In comparison, previous X-ray telescopes were capable of focusing X-rays to five arc seconds. The Advanced X-ray telescope's resolving power is 10 times greater.

"Images from the new telescope will allow us to make major advances toward understanding how exploding stars create and disperse many of the elements necessary for new solar systems and for life itself," explains Harvey Tananbaum, director of the AXAF Science Center at the Smithsonian Astrophysical Observatory, Cambridge, Mass., who is responsible for the telescope's science mission. "We will observe X-rays generated when stars are torn apart by the incredibly strong gravity around massive black holes in the centers of galaxies."

On a larger scale, the telescope will play a vital role in answering fundamental questions about the universe. "The superior quality of the mirrors will allow us to see and measure the details of hot gas clouds in clusters of galaxies, giving us a much better idea of the age and size of the universe," indicates Leon Van Speybroeck, a telescope scientist at the Smithsonian Observatory.

The Advanced X-ray Astrophysics Facility is scheduled for launch in August, 1998, and will join NASA's Hubble Space Telescope and Compton Gamma-ray Observatory in exploring the universe.
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Title Annotation:NASA's Advanced X-ray Astrophysics Facility will deliver resolving power ten times greater than that of previous x-ray telescopes
Publication:USA Today (Magazine)
Article Type:Brief Article
Date:Jun 1, 1997
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