Coelostat
The Coelostat or Zölostat is an auxiliary instrument in practical astronomy to track fixed- direction telescopes - especially tower telescopes - the daily rotation of the sky. For this purpose, two suitably arranged and movable plane mirrors are mostly used. In the Gabriel Lippmann nomenclature, a Coelostat is characterized by the fact that the tracking does not rotate the image field. This is how coelostats differ from heliostats , uranostats and siderostats, which have the same task but are slightly different in structure.
By means of the two movable mirrors of the coelostat, the light from the object to be observed, in particular the sun , is deflected in such a way that it always falls into a stationary observation device. Since you only have to move the two mirrors with this method, very large solar observation systems can be implemented. The actual observation device ( lens telescope or reflector telescope ) may in particular have a very long focal length , since it does not need to be moved for tracking.
With the Jensch coelostat, named after its inventor Alfred Jensch , the entire sky can be observed without the two mirrors shading each other. The setting of celestial positions in the coordinates declination and right ascension is possible in the same way as with a conventional equatorial telescope mount . But it has to be particularly precise due to the double reflection.
literature
- Rolf Riekher: Telescopes and their masters . 2nd Edition. Verlag Technik, Berlin 1990, ISBN 3-341-00791-1 , p. 255.
- Spektrum.de
Individual evidence
- ^ Gabriel Lippmann: Sur un coelostat, ou appareil à mirroir, donnant un image du Ciel immobile par rapport à la Terre . In: Comptes rendus des scéances hebdomadaires de l'académie des sciences . tape 120 , no. 1 . Paris May 13, 1893, p. 1015-1019 .
- ^ AA Mills: Heliostats, Siderostats, and Coelostats: A Review of Practical Instruments for Astronomical Applications . In: Journal of the British Astronomical Association . Vol. 95, NO.3 / APR, 1985, pp. 89 .