Nov 19 1978

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HEAO 2 had radioed back its first picture Nov. 18, an image of x-rays coming from the edge of what may be a black hole, the Washington Star reported. When the picture first appeared on a GSFC television monitor as a collection of bright dots against a black background, scientists and engineers were described as "ecstatic." Dr. Riccardo Giacconi of the Smithsonian Astrophysical Observatory said: "The significance of today's event is that for the first time x-ray astronomy has become of age, and it has achieved the kind of resolution and sensitivity which has been traditional in the fields of radio and optical astronomy." He said the x-ray telescope on HEAO 2 should be able to detect x-rays from objects two-thirds of the way toward the edge of the universe, meaning that the satellite would be seeing radiation created roughly 10 billion yr ago. Giacconi added, "The scientific significance is what it tells us we are going to get in the future," and noted the telescope was 100 to 1000 times more sensitive than previous x-ray detectors placed above earth's atmosphere.

The picture reconstructed by computer from data radioed back by the satellite was a test to demonstrate the capability of the telescope, which had a 23-in-wide mirror and an 11-ft focal length. Target for the test was a star system in the Milky Way galaxy called Cygnus X-1, selected because of its well known location and its brightness. Cygnus X-1, 6000 light-yrs away, also happened to be the best candidate for a black hole; observations by a smaller x-ray satellite had shown that its x-ray emissions were unlike those seen from other objects. (W Star, Nov 19/78, A-13)

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