The elevation range of a telescope is a measure, typically in degrees of how high and low the telescope can be pointed as an angle above the horizon, 0 degrees being toward the horizon, 90 degrees being vertical. The elevation range may limit how much of the sky can be viewed at a given time, and also when portions of the celestial sphere can be viewed. An example might be 5-80 i.e., "from 5° to 80°". The term can be applied to non-optical telescopes such as radio telescopes. The "door" (shutters) of an observatory (through which the telescope is pointed) may impose limits on the facility's elevation range.