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Green Bank Radio Observatory

Green Bank is one of the big observatories of the National Radio Astronomy Observatory (NRAO; external link) in the US. It is the site of the Green Bank Telescope (GBT; external link), which, together with the Effelsberg 100-m radio telescope, is the largest fully steerable dish of the world. As an example of the other, older telescopes at the Green Bank observatory, I show here the 43-m telescope, a huge equatorially mounted dish. There are more telescopes, not shown in photos here.

The Green Bank 43-m telescope on a winter's day.

Historical antennas

Green Bank also hosts two historical radio antennas: A replica of the antenna with which Karl Jansky discovered in 1932 radio frequency interference of his communication experiments, which he later identified as coming from the centre of the Milky Way galaxy (next photo) ...

Replica of the rotatable antenna used by Karl Jansky to investigate the source of interference hampering radio communication transmissions.

... and Grote Reber's parabolic antenna from 1940, the first real "dish" used for radio astronomy (photo below).

Grote Reber's revolutionary parabolic antenna, the first focussing radio telescope, from 1940.

As one can see, I visited the observatory on a cloudy winter day. And, from the lack of a photo here one can also tell that I visited after the collapse of the old 300-ft (91 m) telescope in 1988, which by now is also almost historic (certainly anecdotal)...