coelostat

American  

[see-luh-stat] / ˈsi ləˌstæt /

noun

Astronomy.

1. an apparatus consisting of a mirror driven by clockwork, used to enable a fixed telescope to keep the same area of sky in its field of view by compensating for the apparent rotation of the celestial sphere.

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coelostat British  

/ ˈsiːləˌstæt /

noun

1. an astronomical instrument consisting of a plane mirror mounted parallel to the earth's axis and rotated about this axis once every two days so that light from a celestial body, esp the sun, is reflected onto a second mirror, which reflects the beam into a telescope Compare siderostat

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Etymology

Origin of coelostat

1895–1900; coelo- (for Latin caeli-, combining form of caelum sky) + -stat

Example Sentences

The corona was photographed by Professor Barnard, at Wadesborough, North Carolina, with a 61-1/2-foot horizontal "coelostat."

From A Popular History of Astronomy During the Nineteenth Century Fourth Edition by Clerke, Agnes M. (Agnes Mary)