Re: [ATM] Thermal mirror deformation -fan on both sides

[Daniel Fundo <fundo@bellsouth.net>]

<<  I know that most of the ATMs are pragmatic, and are more inclined to
building than theorizing.  >>

At this time of the year, and especially THIS year, my problem is
WARMIING my mirror!  

I keep my telescope inside my home, as I am sure most members do who
can't afford an observatory.  My house is air conditioned, so the 'scope
is at approx 76 degrees when I take it outside.  Here in the South and
over most of the middle part of the U.S., the temps have been on the
warm side this year.  It is not unusual for the temperature to be in the
upper 80's after 10:00PM.  If the humidity is over 60%, commonly, then
the dewpoint is at 73 degrees or lower!  Guess what happens?  Can you
say "Dew".... sure you can.  It can take up to 30 minutes for the
moisture to evaporate, unless I use other means.

All of my mirrors are Pyrex (R), so except for the moisture, I can
usually go right to observing when I go out.  Transparency has been
terrible lately, and seeing doesn't matter if you can't get through the
haze.  Under these conditions, what does thermal deformation amount to
in regard to actual observing?  

It may mean something to the CCD crowd, but us eyeball observers have
enough accommodation in our natural photon receptors to adjust.

In friendship
*****-----
Dan F.
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