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Originally Posted by iceman
That's better..
Nice page Anthony, a very elaborate system you've developed there! I guess you subscribe to the theory that the mirror must be absolutely at the ambient temperature?
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Absolutely!! :-)
I've seen the difference that it makes in practice - on Jupiter earlier this year there were tiny storms and swirls that completely disappear when the mirror is even a teeny bit warmer than the air next to it.
From my own research and stuff I've read from other people it seems that the boundary layer between cold and warm air next to the mirror can distort the apparent paraboloid surface by a couple of wavelengths, making it perform like a very poor mirror indeed.
I think this is the "secret" to why some people get amazing images and other don't. A mirror that's thermally out of balance is going to perform so badly that it really doesn't matter how well you've collimated or focussed...
Smaller mirrors are easier to cool, but once you get to 10" or larger then this can become a big problem - especially here in Canberra.
Bird