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Green Bank
Green Bank Original location, in West Virginia, of the National Radio Astronomy Observatory. In Nov. 1988, the 91-meter diameter meridian transit telescope at Green Bank collapsed after 26 years of use. Its replacement – the Green Bank Telescope (GBT) – is the world's largest fully steerable dish, with a height of nearly 145 meters and an aperture of 100 by 110 meters. The subreflector and prime-focus feed for the dish is supported on a long boom arm extending over the top edge of the structure and offset so that it does not block the view. The primary surface is composed of 2209 panels whose position can be determined and adjusted using laser distance-measuring equipment; the adjusted surface should have an accuracy of 220 μm and operate at up to 86 GHz. |