thermal stabilization of dobsonian

[Chippy3476]

Hi all,
I was just wandering how to thermal satbilize my 8" dobsonian? How long to leave it outside before using, do I need to take all dust caps off or just place outside with caps on, if caps are off what about bugs getting in?
Thanls all
Dan

[barx1963]

Daniel
An 8" will cool down relatively quickly, I usually just left my 8" outside for about 1/2 an hour unless there was a large temp difference between inside and outside. If your scope has a fan that will speed up the process.
Taking of the dust caps will also speed things along. As for bugs getting in, they will get in anyway when you use the scope, so I wouldn't spend any time worrying about the cool down time. Leave the tube horizontal so the mirror is vertical reduces the risk of any dust or dirt settling on the mirror.

Malcolm

[Chippy3476]

Thanks mate,
Another question is, if dust gets on the mirror how do I clean it off? Should you ever clean a mirror or will it dmage it? Sorry if this is a silly question.
Dan

[barx1963]

Daniel
Not a silly question and one of the most asked and often debated question.
The short answer is, the best thing to do is learn to live with a little dirt. A bit of dust will have almost no effect on the mirror or the image it gives. If you pull the mirror out each time it gets a bit on it you are only increasing the risk of dropping the mirror, dropping something on the mirror or damaging the cell which can all do real harm.
If it is really dirty, a guide to washing written by Mike is here http://www.iceinspace.com.au/63-345-0-0-1-0.html. The coatings on mirrors are actually fairly robust so if they really need a clean, it can be done quite safely.

Cheers

Malcolm