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.
- Compare siderostat.
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How to use coelostat in a sentence
It will be laid comfortably flat on the ground, and the rays of light reflected into it by a coelostat.Astronomical Discovery | Herbert Hall Turner
British Dictionary definitions for coelostat
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
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012