Telescopes and temperatures

[Nikodemuzz]

Hi all!

I have been wondering lately about what, if anything, high temperatures could potentially do to telescopes. The reason for this is that I have my C11 set up on my glass-windowed balcony. I like to leave the scope assembly there so that I don't have to balance and align again every night. The balcony faces West, which means that when the weather is nice, the Sun shines to the balcony all late afternoon right until it sets. Especially if the windows are shut the temperature on the balcony can be quite high indeed. I have covered the OTA with a blanket to shield it from direct sunlight, but still it gets quite warm. Now, the obvious drawback from this is that I need to wait a fair bit longer for the scope to cool since it gets nicely warmed up just before sunset, but could there be other more serious consequences? For example deterioration of the mirror coatings and such?

How do you guys with permanent set-ups in garden observatories control the temperatures in them? Do you take any measures in the first place? Surely those domes or sheds also get quite hot during a sunny day, but is there any real harm in that?

[glowjet]

So long as it is a dry heat, I would doubt there will be anything to worry about, especially as the scope is shaded from direct Sunlight. Small obsy`s are bound get quite hot inside on those very warm days we get on the odd occasion here in the UK.

If you are really concerned, will it cost a lot to run a small thermostatically operated fan unit, when temperatures reach the higher regions, to create some air circulation. If anyone has had problems here, I am sure there will be some other comments to come

[Peter Drew]

My main concern would be grease in the shade tube assembly getting runny in the heat and dripping on to the mirror or corrector plate. I would recommend pointing the main tube upwards. 

[Fish]

My little obsy gets hot and gets the sun all day , its not caused any problems for me . Just be aware of the point above about grease and scope storage .

[LukeSkywatcher]

I store my 8SE in my bedroom beside but not infront of a window. I have it horizontal on the mount and a towel thrown over it. Its close to a radiator but that is never on cuz i hate heat in my bedroom.

[mcolbert]

FWIW, whilst I store my ota in its box, several people I have known in Sydney who had small metal garden sheds (for their scopes), never mentioned any problems.  Temperatures in summer - as it's approaching now, can reach the mid 40's © so you can imagine what their sheds are like at sunset! 

michael