Quote:
Originally Posted by clive milne
Professional observatories take a completely different approach to thermal management. They pre-chill the telescope prior to an observing session...
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Sure. Thermals are produced by a temperature gradient and the thermals are specifically the result of convective cooling.
Until recently its quite safe to say that everyone was of the traditional view that the only way to stop these thermals was to eliminate the temperature gradient, ie everything had to be close to the ambient external air temperature.
This is certainly true for newtonians and observatories - because they're invariably using large reflectors with open tubes and under a dome with a huge open slit. There is however at least one I know of in the arctic circle that doesn't cool theirs - it uses a high-grade plastic film across the dome slit - like glad-wrap but better - to retain warm air in the dome despite the outside temps being subzero.
However there is a second way - stop the flow of heat using insulation. This only applies to scopes with closed tubes that display a tube current - specifically SCTs and Maks and I suggest that has always been obvious in these threads and those on CN. Insulating the OTA stops the convention, very effectively, as does insulating a house.