Green Bank Observatory

The Green Bank Observatory (GBO) is a radio observatory located in Green Bank, West Virginia, which is the location of the Green Bank Telescope (GBT). It also hosts retired, historic telescopes, including the Green Bank 140 Foot Telescope, which was revived for some use 2005-2019. Its telescopes are single-dish (i.e., not arrays) but do participate in very-long-baseline interferometry observations. Previously at the site was the Green Bank 300ft Telescope (GB300), the predecessor of the GBT, and the observatory has long been the site of the largest steerable radio telescope dish. The observatory site is surrounded by a radio quiet zone, a region where radio transmission is limited (the US's National Radio Quiet Zone, NRQZ).

The observatory was the original National Radio Astronomy Observatory (NRAO). When the NRAO expanded, GBO became just one of the NRAO sites. Since 2016 when the NRAO chose to focus on newer projects, the GBO has continued as an independent organization.