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Why Do You Need So Many Radio Telescopes?

-- | May 8, 2016

Question: Why do you need so many radio telescopes? Do they all receive exactly the same frequency? How are the signals integrated into something meaningful? — Ray

Answer: You basically hit on a part of the answer in your second sentence. Different radio telescopes are designed to make measurements at different frequencies. For example, we build very high-performance antennas to make measurements at high frequencies. At lower frequencies, we can relax these performance requirements and make them larger. Another reason for building more than one radio telescope is that we have basically two different techniques to make radio astronomical measurements. One is to just make measurements with a single antenna (like the Green Bank Telescope), and the second is to electronically connect many antennas into an array of radio telescopes (like the Very Large Array) in order to increase the amount of collecting area the spatial resolution on the sky of the measurements we make. Finally, since one cannot see the entire visible sky from one place on Earth we need to place telescopes at different places on Earth to be able to observe in all directions.

Jeff Mangum

The National Radio Astronomy Observatory is a facility of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
	Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.
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