The Green Bank Telescope is a 100 meter (330 ft) radio telescope built by NRAO in Green Bank West Virginia, USA. It is one of the biggest fully steerable radio telescopes in the world and it has the sensitivity to see further into our universe than ever before. It operates at frequencies up to 100 GHz. This page contains a brief photographic tour. For technical details you should look at NRAO's website.

	The GBT seen from the air The GBT is of an unusual design, in that the feed-arm (the big strut to the right of the main mirror that holds all the receivers) is off axis. This means that it does not get in the way of incoming light, giving the telescope a cleaner view of the sky.
	The active surface In order to work at frequencies up to 100 GHz the surface has to be kept accurate to 0.3 mm. As the telescope moves, gravity would distort the surface by far more than this. To get around this problem the surface is made up of 2004 panels. Models and measurements of how the telescope distorts with changes in temperture and elevation are used to adjust pistons at the corner of each panel to bring the surface back to the right shape.
	The feedarm end The feedarm holds all of the detectors that perform the GBT's sensitive measurements. All of the radiation reflected off of the main surface arrives here thanks to the precise shape of the main dish. It reflects off of the subreflector (the second, smaller dish visible at the top of the feedarm, and then is focused into the receiver room.
	The rotating turret A technician works on the rotating turret, which is housed in the receiver room. This turret contains several different receivers, each of which is used to measure different frequency bands. The turret rotates so that the appropriate receiver is exposed to the incoming radiation. This makes it very easy to change the receiver and thus produce different measurements easily. MUSTANG fits into one of the smaller slot.
	The top of the receiver room Standing on top of the receiver cabin you can see the giant horn feeds used on two of the receivers. From this point, one has a tremendous view of the surrounding land.
	The GBT in motion The GBT is a fully steerable telescope. The movie on the left shows the telescope being moved along its azimuthal axis. This is an extraordinary capability for such a large telescope, but crucial to the scientific value of the telescope.
	Just how big is 100 meters? This graphic shows clearly just how big the GBT actually is, taller than the Statue of Liberty and nearly as tall as the Washington Monument.

pictures from NRAO