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Re: (IAAC) Obj: Jonkherre 900 (PK 194+2.1) - Inst: 51cm f/10 classical Cassegrain



Art;
I am more than willing to say that my rating system is subjective,
but it has become internally consistent over the years.  My
observing buddy just started years ago saying "well this is
a 5 out of 10 night or Wow, this is a 9 night.  I use a view
of the planets and how much the limb of the planet moves at
about 200X, combined with views of known deep sky objects to
create the seeing rating.  I use views of known areas of
the sky--Little Dipper, Cepheus and the general look the width
and number of stars seen in the band of the Milky Way as
the contrast or transparency rating.  So, a location where
I can just barely see the Milky Way is a 3 or 4, if it is
visible but the dark lane is not prominent is a 5 or 6 and
if the band of Our Galaxy is wide and the dark lane stands
out nicely is 7 or 8 and if it is huge and the dark lane is
impressive, then a rare 9 or 10.  Obviously, the best rating
only happen far from city lights and up in the mountains.
Hope that helps;
Steve Coe

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