[AZ-Observing] Re: Recording Seeing Conditions (was WOW!)
- From: Andrew Cooper <acooper@xxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Mon, 11 Jul 2005 23:55:42 -0700
I have been following this thread for a while now and just have to weigh
in with my disagreement. Arbitrary, unscientific, crude seeing and
transparency scales certainly do have a role for the visual observer! I
keep notes of my impressions of the conditions for my observations. This
gives me something to go on when reviewing my notes later, sometimes
years later. Was the night good or bad? Why did I not see the dust
lane in NGCxxxx or did see the central star in PNxxxx? Do I need to
re-observe ICxxxx under darker skies to properly appreciate it?
I use something like Pickering's scale for seeing and a visual estimate
of the dimmest stars I can see near zenith for my notes. (I don't use
the pole because I am so often south of Tucson or Phoenix) It's not
very calibrated, it isn't rigorously controlled, but it gives me some
sort of scale when looking back to put my notes into perspective.
I generally don't share my numbers with others beyond it was a good
night, or transparency was great but seeing looked like we were viewing
from the bottom of Old Faithful, every few minutes the stars turned into
beachballs. I usually give an average SE Arizona night a 6 or 7 for
seeing and a 5.5 to 6.5 for transparency. Consider a little standard
distribution statistics and this makes perfect sense. I have seen a 10
for seeing precisely two times.
We need something, I am not always going to hook in a CCD camera and do
a measurement of the FWHM to figure out the seeing in arcseconds. Such
data has it's place and I appreciate it when available. But when
standing by a telescope I need something, and it needs to be quick,
simple and need not be horribly accurate. The only important thing
that it be reasonably consistent. Looking at a star at high mag and
looking at zenith with a star chart in hand fits the bill.
Andrew
Andrew Cooper
----------------------------------------------------
http://www.siowl.com
Brian Skiff wrote:
> <>
> That's why you avoid these arbitrary scales altogether, and use
> physical units you can actually measure, specifically arcseconds.
>
> Brian
>
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