Green Bank Telescope
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Green_Bank_Telescope.jpg
The Robert C. Byrd Green Bank Telescope (GBT) is the world's largest fully mobile radio telescope. It is part of the National Radio Astronomy Observatory (NRAO) at Green Bank, West Virginia (USA). The telescope honors the name of Senator Robert C. Byrd.
The telescope sits at the heart of the United States national radio quiet zone, a large area where all radio transmissions are either limited or banned outright, to help the telescope function properly.
Description
The surface area of the GBT is 100 by 110 meters with a separate actuator for each of the 2,004 surface panels. The panels are made from aluminum to a surface accuracy of less than 0.003 inches (76.2 micrometers) RMS. Infrared lasers are used to measure the position of each plate so that if one is to move out of place the actuator can move it back into its proper position, resulting in a surface that can be kept in an optimal state throughout an observation with the telescope. A laser alignment system also allows for precise knowledge of the positioning of the dish by using reflectors in the mountains and around the base of the telescope itself.
The telescope is unusual in that the mirror is not a symmetrical dish, but is a section of a much larger parabolic figure with the receiver where the prime focus of the entire mirror would be. As a result, the support for the receiver does not in any way obscure the mirror's view of the sky.
Related topics
External links
- NRAOGB: Green Bank Telescope (http://www.gb.nrao.edu/GBT/GBT.shtml) - official site.
- Aerial photo that happened to catch telescope while it was under construction (http://terraserver-usa.com/usgsentry.aspx?T=1&S=10&Z=17&X=3006&Y=21272&W=3&qs=%7cgreen+bank%7cwv%7c)