Astron. Astrophys. Suppl. Ser. 130, 369-379
Send offprint request: T.H. Legg
Herzberg Institute of Astrophysics, National Research Council of Canada, 100 Sussex Drive, Ottawa, K1A 0R6, Canada
Received March 11; accepted December 2, 1997
A new type of radio telescope is proposed which may make very large telescopes more affordable. The telescope is considered to be one of several identical elements that form a synthesis array. It is composed of an almost flat primary reflector that is slightly adjustable in shape and made up of identical square flat panels supported by the ground. A very long focal length imposes the unusual condition that the receiver be carried by an airborne vehicle such as a powered, helium-filled balloon. The position of the balloon is measured and controlled as accurately as possible and residual errors in the balloon's position are dealt with in two ways. Errors of a few metres are corrected by moving the receiver feed point electronically. Larger errors are corrected by adjusting the primary reflector so as to move its focal point to follow the balloon. These features maintain telescope efficiency and correct pointing so long as the balloon lies anywhere within a large volume surrounding its ideal position. The problem of controlling the balloon position is thereby substantially eased. The telescope has the wide sky coverage needed for synthesis observations and an estimated optimum diameter in the range 100 to 300 m. It will operate from decimetre to short centimetre wavelengths, or, with smaller panels, millimetre wavelengths.
Key words: telescopes -- instrumentation: interferometers
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