1. Plural of coelostat: an astronomical instrument consisting of a mirror or prism that rotates to track the sun or a star and direct its light into a fixed telescope or spectrograph.
Usage: technical; astronomy

Examples

• The observatory uses coelostats to maintain a constant image of the sun for continuous observation.
• Modern solar telescopes often employ coelostats to feed light into stationary spectrographs.
• The rotating mirrors in coelostats compensate for Earth's rotation and the apparent motion of celestial objects.
• Astronomers installed multiple coelostats to study different wavelengths of solar radiation simultaneously.