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Proceedings Paper

Effects of heat sources in the telescope beam on astronomical image quality
Author(s): Jacques Maurice Beckers; Jorge Melnick
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Paper Abstract

Heating of the air in astronomical telescopes is known to have a deteriorating effect on the image quality. Main heat sources are the primary mirror and localized electrical components in or near the light beam. To evaluate the effects of these localized heat sources we measured the image quality deterioration at the focus of the ESO-La Silla 2.2 meter telescopes with variable amounts of heating of a dummy electronics box and of a bar simulating one of the secondary mirror spiders. The effects on the FWHM of the image profile turned out to be remarkably small. Most of the effect of the heating showed up in the removal of energy of the core into the far wings of the image profile. For a heat input of 560 Watts (resulting in an excess temperature of 60 K) the amount of energy removed amounted to 13%. This behavior can be explained by a model in which the heating destroys the wave-front over only a part of the aperture while leaving it unaffected over most of the aperture. With such a model we predict the amount of energy removed by a 500 Watt heat source in an 8 meter telescope to be only 1%.

Paper Details

Date Published: 1 June 1994
PDF: 3 pages
Proc. SPIE 2199, Advanced Technology Optical Telescopes V, (1 June 1994); doi: 10.1117/12.176213
Show Author Affiliations
Jacques Maurice Beckers, National Solar Observatory (United States)
Jorge Melnick, European Southern Observatory (Germany)

Published in SPIE Proceedings Vol. 2199:
Advanced Technology Optical Telescopes V
Larry M. Stepp, Editor(s)

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