Effect of atmosphere on viewing

Does anyone know of any data/links that shows how much the existence of the
atmosphere (as an object) affects viewing?

It's a quite general question, so I don't know the exact English terminology
to search under, in yahoo. Ideally, I would like to know how the sky would
look had there been no atmosphere, visually. How much brighter for example
(by order of magnitude) would certain celecstial objects be and stuff like
that.

For example, if the 200" scope at Palomar was moved to the moon, how far
down could it photograph, intead? (28 vs 23, etc)

Thanks in advance and happy observing!
--
Ioannis Galidakis
http://users.forthnet.gr/ath/jgal/
------------------------------------------
Eventually, _everything_ is understandable

Ioannis wrote:
Does anyone know of any data/links that shows how much the existence of the
atmosphere (as an object) affects viewing?

It's a quite general question, so I don't know the exact English terminology
to search under, in yahoo. Ideally, I would like to know how the sky would
look had there been no atmosphere, visually. How much brighter for example
(by order of magnitude) would certain celecstial objects be and stuff like
that.

For example, if the 200" scope at Palomar was moved to the moon, how far
down could it photograph, intead? (28 vs 23, etc)

Not anything like that. With respect to this question, I think the
phrase you're looking for is "atmospheric extinction." When looking
through the atmosphere to the zenith, extinction levels are small at
visible wavelengths--maybe a couple of tenths or so. That increases
to the UV end and decreases to the IR end. When looking at an angle
through the atmosphere, it's a reasonable approximation (except for
very low angles above the horizon) to assume the Earth is flat. g
That is, at an angle a above the horizon, assume you are looking
through sec a atmospheres.

There is also the issue of seeing, both long-term and short-term. The
long-term impact on imaging was looked at with some rigor by Fried;
search for "Fried parameter" or "Fried length." If I recall correctly,
that's the aperture at which a long-term PSF is diffraction-limited
(something along those lines).

With visual use, it takes a bit more work to characterize, because if
you're willing to wait long enough, you will get a flash of steady
air. I'm sure it's been looked at, but I'm not aware of any specific
work...

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

Ioannis wrote:
Does anyone know of any data/links that shows how much the existence of the
atmosphere (as an object) affects viewing?

It's a quite general question, so I don't know the exact English terminology
to search under, in yahoo. Ideally, I would like to know how the sky would
look had there been no atmosphere, visually. How much brighter for example
(by order of magnitude) would certain celecstial objects be and stuff like
that.

For example, if the 200" scope at Palomar was moved to the moon, how far
down could it photograph, intead? (28 vs 23, etc)

Not anything like that. With respect to this question, I think the
phrase you're looking for is "atmospheric extinction." When looking
through the atmosphere to the zenith, extinction levels are small at
visible wavelengths--maybe a couple of tenths or so. That increases
to the UV end and decreases to the IR end. When looking at an angle
through the atmosphere, it's a reasonable approximation (except for
very low angles above the horizon) to assume the Earth is flat. g
That is, at an angle a above the horizon, assume you are looking
through sec a atmospheres.

There is also the issue of seeing, both long-term and short-term. The
long-term impact on imaging was looked at with some rigor by Fried;
search for "Fried parameter" or "Fried length." If I recall correctly,
that's the aperture at which a long-term PSF is diffraction-limited
(something along those lines).

With visual use, it takes a bit more work to characterize, because if
you're willing to wait long enough, you will get a flash of steady
air. I'm sure it's been looked at, but I'm not aware of any specific
work...

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

Ioannis wrote:
Does anyone know of any data/links that shows how much the existence of the
atmosphere (as an object) affects viewing?

It's a quite general question, so I don't know the exact English terminology
to search under, in yahoo. Ideally, I would like to know how the sky would
look had there been no atmosphere, visually. How much brighter for example
(by order of magnitude) would certain celecstial objects be and stuff like
that.

Check out: http://www.astropix.com/HTML/L_STORY/SKYBRITE.HTM

You'll find several Brian Skiff articles that answer at least some of your
questions.

Regards,

Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net
=============
Email: Remove "ic" from .comic above to respond

Ioannis wrote:
Does anyone know of any data/links that shows how much the existence of the
atmosphere (as an object) affects viewing?

It's a quite general question, so I don't know the exact English terminology
to search under, in yahoo. Ideally, I would like to know how the sky would
look had there been no atmosphere, visually. How much brighter for example
(by order of magnitude) would certain celecstial objects be and stuff like
that.

Check out: http://www.astropix.com/HTML/L_STORY/SKYBRITE.HTM

You'll find several Brian Skiff articles that answer at least some of your
questions.

Regards,

Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net
=============
Email: Remove "ic" from .comic above to respond