[AZ-Observing] Re: Mars-Moon Conjunction - Now Pickering Scale
- From: "William R Wood" <wmrwood@xxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Thu, 17 Jul 2003 08:59:46 -0700
Try this page for a reference as to the Pickering scale:
http://uk.geocities.com/dpeach_78/pickering.htm
I keep a copy of this animation on my laptop to use in the field but a
static version can be printed out too. After a lot of practice I have
become pretty good estimating seeing based on this scale. I am working on
comparing the Pickering scale method to Brian Skiff's equal double star
method of evaluating seeing.
The Pickering scale is based on a 5" refractor. I haven't been able to do
side-by-side comparisons but in night-to-night comparisions there is a
significant difference between my 90mm f/5.6 refractor and my 128mm f/8.1
refractor. The smaller the scope and/or shorter the f/l, the better the
seeing looks. I don't know whether aperture or focal length is the more
important factor. The difference is even more dramatic going from the 5"
refractor to a 10" f/12 D-K Cassegrain. My ususal rating in the 10" is more
like 3/10.
Regards,
Bill Wood
Fountain Hills, AZ
> -----Original Message-----
> From: az-observing-bounce@xxxxxxxxxxxxx
> [mailto:az-observing-bounce@xxxxxxxxxxxxx]On Behalf Of Andrew Cooper
> Sent: Thursday, July 17, 2003 2:29 AM
> To: AZ-Observing mailing list
> Subject: [AZ-Observing] Mars-Moon Conjunction
>
>
> The seeing was poor to fair, a pickering 5 perhaps judging from the airy
> disk. Need to print out a version of the Pickering Scale for the
> reference section of my observing notebook. My refractor being similar
> to the instruments he designed the scale for.
>
>
> Good night,
>
> Andrew
>
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