siderostat


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siderostat

(sid -ĕ-rŏ-stat) A flat mirror that is driven in such a way as to reflect light or infrared radiation from a celestial body to a fixed point, such as a spectrograph slit at the coudé focus of a telescope, over the duration of an observation. A siderostat is often installed outside the main dome of an observatory and can be used with a coudé spectrograph, say, at the same time as the main telescope is being used to study a different field of view. Siderostats often have computer-driven altazimuth mountings.

Siderostat

 

an auxiliary astronomical instrument whose principal component is a plane mirror. The mirror moves in such a way that it reflects the light rays from a heavenly body in a fixed direction, in spite of the apparent diurnal rotation of the celestial sphere. A siderostat is used to direct the rays of a heavenly body into a fixed telescope. The mirror of the siderostat rotates around two mutually perpendicular axes. A siderostat used to observe the sun is called a heliostat. A primitive form of siderostat was used as early as the 17th century. In the 18th century the use of a clockwork mechanism was introduced for the rotation of the mirror.

siderostat

[′sid·ə·rə‚stat]
(optics)
A more precise model of a heliostat; the siderostat uses a modified mirror mounting so that the image of a star is kept steady while the rest of the field is in rotation about the center.
References in periodicals archive ?
Casting the massive, 2-meter siderostat mirror proved difficult.
The siderostat stood 10 meters tall at the north end of the Foucault Gallery in the Paul Gautier Room, under sections of roof and walls that could be slid to the north and south to expose the sky.
Deloncle himself tested the telescope on the first clear night when the Moon was observable with the siderostat.
Opening the roof took six to eight people, he reported, but only two were needed for observations: one adjusting the siderostat and the other adjusting the optics at the eyepiece end.
The siderostat mirror went to Paris Observatory, where it has long been displayed in the history building.
A siderostat mirror followed the turning sky and directed light into a 491/4-inch f/48 refractor, fixed horizontally.
In order to move beyond NPOI's already impressive resume of accomplishments, the Naval Research Lab (NRL) plans to replace the current siderostats and telescopes with larger diameter telescopes.