[AZ-Observing] Re: Tonight

Jeff,

Thanks for the photometry information.  Since I am unfamiliar with photometry, 
I wonder if you could achieve the photometric stability that you quantified 
from last night's run even if the seeing were poor.  The "fast" seeing that 
we've been discussing does not result in much "flickering" as much as it just 
increases a star's "blur" (for lack of a better terms).  So it seem like over 
the course of the integration time required for your photometry, the average 
brightness would be quite repeatable, as you observed.

I am familiar with visual observing, however.  The fast-moving air currents 
that several of us noticed last night are typically more global than local to 
the site, whereas mountain drainage into basins results in slower-moving seeing 
cells.  So perhaps despite the excellent photometric conditions you 
experienced, the seeing for visual observers was not so great even at your 
site.  After all, your 12mm eyepiece would yield a magnification of only 170x, 
which is just barely enough to magnify the Airy discs enough notice seeing 
effects.

Regarding FWHM seeing measurements, back when I was imaging from my backyard 
with a 13" and ye olde ST-7 CCD camera, the values output by MaximDL software 
correlated quite well with the visually observed seeing conditions.  On the 
best nights, I measured seeing in the neighborhood of 1.5", and it was apparent 
at the eyepiece.  More typically, I was getting numbers nearer to 3".

Tom
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