Re: [ATM] fans

[Mark Holm <mdholm@telerama.com>]

> Better yet, pump out the air and fill the tube with vacuum

You know, this has been done.  More than once.

http://www.kis.uni-freiburg.de/kisobservatorien_e.html

http://www.nso.edu/nsosp/pr/vtt.html

http://www.solarphysics.kva.se/first-light.html

 From the last web page,

"Modern solar telescopes are either vacuum telescopes, filled with 
helium or use careful control of the optic's temperature to reduce 
heating of the air in the telescope."

Hmmm.  Which of these three methods sounds most practical for light 
weight, large aperture, transportable telescopes?

---
Mark Holm
mdholm@telerama.com

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