continuous viewing zone

A telescope's continuous viewing zone (CVZ) is that region of the celestial sphere that the telescope can view at any time. For space missions, areas sometimes blocked by the Earth or Sun would be excluded. The concept is of less use for Earth-bound telescopes, but seems relevant to radio telescopes not close to the equator, i.e., a region around the pole can be viewed day and night all year. A telescope proposal may specify the CVZ needed to meet the proposed observation's goals.