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instrument used in solar telescopes to orient and focus sunlight along a fixed direction. A typical heliostat consists of a flat plane mirror and a curved parabolic mirror. The plane mirror is mounted along an axis parallel (i.e., equatorial) to the Earth and rotated slowly by a motor to reflect light from the Sun. The parabolic mirror focuses the reflected rays into the telescope along a fixed direction while the Sun traverses the sky. Therefore, as the telescope's field of view rotates, different celestial objects move quickly into view