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 Post subject: Altitude observations
PostPosted: Mon Jan 16, 2017 6:05 pm 
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Hi all astros, My 1st. ?
Is there any advantage to be had in 'seeing' from altitude ?

e.g 950 mtrs. Espezel,Aude 11340 France.

02 01 17 E 42 49 24 N

VincentVan.


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PostPosted: Tue Jan 17, 2017 2:38 pm 
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Location: Lancashire
Modern observatories are often located on mountain tops for their freedom from cloud and for the more stable atmospheric conditions and temperature gradients. The world-renowned Mauna Kea observatories are situated at over 13,000 feet.
For us skywatchers, even a modest hilltop should provide clearer viewing than in a valley bottom. At night, cold air sinks into valleys creating a denser layer of air that has a different refractive index than the air above it. This causes the image to wobble and scintillate were the two air masses meet.

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brian


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PostPosted: Tue Jan 17, 2017 2:41 pm 
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Hi VincentVan (Gogh?).
Welcome.

Yes, there is if it is a plateau.
If a pointed peak there can be air currents.
The main advantage is if it is a dark place.
Vegetation is better than concrete/asphalt for Seeing.

5,000ft to 8,000ft is better.
Above 10,000ft you may need an oxygen bottle.

Regards,
David


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PostPosted: Thu Jan 19, 2017 5:57 pm 
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thanks for the replies. Vangogh is intended.
I am happy to tell you this area is a Plateau.
Most of the vegetation is potatoes and wild flowers.
It is mostly dark but has street lights.
I will have to accept the 2700 to 3000ft .

I am also happy to tell you, that we get many clear nights here!

Now to decide, 10x50 or 15x70 binoculars to start watching with.


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PostPosted: Fri Jan 20, 2017 4:00 pm 
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Either binocular is fine.

Seeing more a scope problem at 100x plus, not a binocular problem.

Maybe you mean Transparency.

Regards,
David


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PostPosted: Sat Jan 21, 2017 10:55 am 
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Hi Brian and David,
I have been reading about averted vision from Sky at Night Mag.
the part about the qualities of the eye are very helpful, as have been your responses
to my post.

perhaps you could enlarge on the term and use of 'transparency.' No hurry as I have
no scope yet. Only an old pair of 7x50 Helios bins.


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PostPosted: Sat Jan 21, 2017 2:47 pm 
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Location: Lancashire
If you already have a pair of 7X50's Vincent, add the 15X70's to them. They'll show very pretty views of the Moon, star clusters and nebulae.

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brian


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PostPosted: Sat Jan 21, 2017 8:24 pm 
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Transparency is the clarity of the air, so you see faint stars or nebulous objects.

Seeing is the steadiness of the image, sometimes best when slightly misty.

Regards,
David


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PostPosted: Mon Jan 23, 2017 6:42 pm 
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Re; transparency. thanks David.

All is clear now, ( pun intended)


Robert. AKA Vincent as username.


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