Definition of coelostat in US English:



  • An advanced version of a heliostat, having a rotating mirror that continuously reflects the light from the same area of sky, allowing the path of a celestial object to be monitored.

    • ‘Moreover, the light reflected by the coelostat is partially polarized, and the amount and character of polarization depends on the incidence angle.’
    • ‘To create rotating images in the full 360-degree range, two sets of coelostats can be combined, each compensating for the dead zone of the other.’
    • ‘The silvered mirrors of the coelostat were pointed to some of the brighter stars beginning in 1905, and the first large-scale spectra of other stars were obtained.’
    • ‘Back in Ottawa, a specially designed shed with a roll off section housed the coelostat for almost 70 years.’
    • ‘This error can be reduced substantially by choosing the coelostat position and time interval.’


Late 19th century: formed irregularly from Latin caelum ‘sky’ + -stat.