Re: [ATM] basic questions about cooling fans

["Bob May" <bobmay@nethere.com>]

Fans are not necssary for viewing although they can help with the problems
of cooling a telescope down to ambient temps.
A thin mirror doesn't need as much cooling as a thick mirror does for
obvious reasons.
The fans can run all the time or can be just used for the initial cooldown,
depending upon the actions of the telescope under either of the regimes.
Most use a 12V fan as this voltage is availble from the car or common
multiple cell batteries and is compatible with other electronics that is
often used as portable stuff.  The fan in the power supply of a PC is a 12V
fan.
For the Venus transit, I'd not worry about a fan as you'll be doing this in
the daylight where there is already a fair bit of turbulence just from the
heating of the ground in the area by the sun making the sky turbulence
fairly strong.  You really don't want to use a large telescope for the Venus
transit but you may if you so desire.  I'll suspect that a 6" scope will be
a nice large scope.  I wish that I had the time and money to take a trip to
Europe with my 200" refractor for that occasion.  Venus shows up as a nice
disk and the recent positions of Venus have been showing an excellent
crescent phase.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net


_______________________________________________
ATM mailing list http://www.atmlist.net/