Green Bank Telescope

The Green Bank Telescope (GBT, sometimes further abbreviated as GB) is a 100-meter radio telescope at Green Bank Observatory (GBO) in West Virginia. The GBO was previously a part of the NRAO (initially, its primary site), but has been independent since 2016. The GBT is the world's largest steerable telescope. The current telescope was completed in 2000, replacing the earlier, collapsed, 1962 Green Bank 300ft Telescope (GB300) (likely in its own time called the "Green Bank Telescope"). The current telescope detects frequencies in the range of 290 MHz to 100 GHz, with prime focus and Gregorian receivers, the former for the longer wavelengths. The reflector is off-axis such that the receivers do not block the signal. Among its present/past instruments:

• MUSTANG and MUSTANG-2 - two successive bolometer arrays.
• Argus - 16-pixel focal plane array (FPA) of W-band radio spectrometers.
• KFPA - K-band FPA.
• PF1 and PF2 - prime focus receivers.
• Gregorian receivers for various bands, among them, C-band and X-band.

Back end instruments have included VEGAS (Versatile GBT Astronomical Spectrometer) and GUPPI. Recent projects include 21-cm line surveys both within the Milky Way, and extragalactic, e.g., redshifted galaxies and also intensity mapping the DEEP2 field.