Green Bank Telescope - unique features and their effectiveness

The Green Bank Telescope (GBT) was commissioned in early 2001 and has resulted in a number of scientific publications during its 13 years' of operation. Pulsars, nature of dark energy, galaxy formation, black holes and Hubble Constant are some examples of research discoveries made with the GBT. The GBT is a fully steerable telescope with a double-offset reflector design. The main reflector is completely unblocked and has a projected aperture of 100 meters in diameter. The subreflector is a section of an ellipsoid 7.55×7.95 meters in size. The telescope operates at prime focus from 290 MHz to 1200 MHz and at secondary focus in the 1.15 GHz to >100 GHz range. The main reflector has about 2000 actuators that are used to compensate for deformations mainly due to gravity and in some cases due to thermal effects.