|
|
A focal point of a telescope on an equatorial mounting, arranged by means of a series of mirrors to lie on the polar axis and so remain stationary regardless of the orientation of the telescope (see illustration). The word "coudé" is French for "elbow". It is necessary to direct the light to a fixed focus when bulky equipment is to be used that cannot be attached directly to the telescope, such as a high-dispersion spectrograph. Large, new-generation telescopes on computer-controlled altazimuth mountings are able to exploit the Nasmyth focus, which is also fixed.
|