See Thru Clouds?

A friend was busting my chops the other day, "Your 8'' is gigantic, but it
can't see thru clouds?"

I got to thinking. On some hazy, overcast nights, you look up and see NO
stars, then you randomly point the scope, and see plenty. So the scope is
capable of some penetration.

Are even the bigger land based "super" scopes limited by cloudcover?

--
BenignVanilla
Pond Site: www.darofamily.com/jeff/links/mypond

BenignVanilla wrote:
A friend was busting my chops the other day, "Your 8'' is gigantic, but it
can't see thru clouds?"

I got to thinking. On some hazy, overcast nights, you look up and see NO
stars, then you randomly point the scope, and see plenty. So the scope is
capable of some penetration.

The other morning I was trying to see Mars at 0100 PDT after it rose
over my house -- and the clouds rolled in. Though I could not see it
with my naked eyes (strange term, that!), I could still see it in the
scope (an 8" Newt EQ).

Phil

Phil Wheeler wrote:
BenignVanilla wrote:

A friend was busting my chops the other day, "Your 8'' is gigantic,
but it
can't see thru clouds?"

I got to thinking. On some hazy, overcast nights, you look up and see NO
stars, then you randomly point the scope, and see plenty. So the scope is
capable of some penetration.


The other morning I was trying to see Mars at 0100 PDT after it rose
over my house -- and the clouds rolled in. Though I could not see it
with my naked eyes (strange term, that!), I could still see it in the
scope (an 8" Newt EQ).

Sat eve I was observing Mars about midnight, low on the horizen above
Reno; clouds were building in the east, and the Mars faded in and out as
wisps of clouds covered it and receeded. The effect was interesting -
the Reno light dome would light up the thin clouds, but the heavy clouds
were too dense and showed as dark. So as I viewed the planet, when the
field of view got darker Mars would fade, but as the fov brightened,
Mars would fade back in; exactly opposite of what my mind was telling me
should happen - in other conditions dark implies better viewing; light
implies poor viewing.

But the final word is: when the clouds are more than wisps, you can't
see squat, even with a 10m eye.

On Wed, 30 Jul 2003 12:35:13 -0400, BenignVanilla penned:
A friend was busting my chops the other day, "Your 8'' is gigantic, but it
can't see thru clouds?"

I got to thinking. On some hazy, overcast nights, you look up and see NO
stars, then you randomly point the scope, and see plenty. So the scope is
capable of some penetration.

Are even the bigger land based "super" scopes limited by cloudcover?

Like most things, it's a matter of degrees. Mid and high level
clouds are usually transparent to some degree. I was once
allowed to keep "my" one-meter class telescope open at Kitt Peak
under a "non-threatening" mid-level cloud deck. I was taking
spectra, so it was just a matter of all the targets being much
fainter than expected. Of course, based on the spectra I was
recording and the images on the guider, at times the cloud cover
was 6 magnitudes thick! So that was pretty useless, too. At
the major observatories, the observing programs are such that
imaging and photometry are mostly useless with any cloud cover
or haze. Spectroscopists can get useful data through thin
clouds, it's just that it takes longer to reach the desired
precision and/or one has to observe only the brightest targets.

Brian Rachford

You can tell your friend that when it comes to seeing through thick
clouds, your 8" is as good as the world's largest telescopes. ;-)

Mike Simmons

BenignVanilla wrote:

A friend was busting my chops the other day, "Your 8'' is gigantic, but it
can't see thru clouds?"

I got to thinking. On some hazy, overcast nights, you look up and see NO
stars, then you randomly point the scope, and see plenty. So the scope is
capable of some penetration.

Are even the bigger land based "super" scopes limited by cloudcover?

--
BenignVanilla
Pond Site: www.darofamily.com/jeff/links/mypond

"Mike Simmons" wrote in message
...
You can tell your friend that when it comes to seeing through thick
clouds, your 8" is as good as the world's largest telescopes. ;-)

Mike Simmons
snip

Prefect. *laugh*

BV.

Mike Simmons wrote in message ...
You can tell your friend that when it comes to seeing through thick
clouds, your 8" is as good as the world's largest telescopes. ;-)

Mike Simmons

I have raised this subject before. When observing planets through
thin fast moving cloud with a 6" f/8 refractor I noted fleeting
increases in detail & contrast (on Jupiter for example). I raised the
possibility that the clouds were frequency dependant and may have been
blocking the excess violet with beneficial effects. Trying to achieve
the same effect with neutrel density filters did not work when the
clouds finally cleared. So it was not simply a light reduction
phenomonem as far as my eyes are concerned. Any thoughts?

Chris.B

"Chris.B" wrote:

I have raised this subject before. When observing planets through
thin fast moving cloud with a 6" f/8 refractor I noted fleeting
increases in detail & contrast (on Jupiter for example). I raised the
possibility that the clouds were frequency dependant and may have been
blocking the excess violet with beneficial effects. Trying to achieve
the same effect with neutrel density filters did not work when the
clouds finally cleared. So it was not simply a light reduction
phenomonem as far as my eyes are concerned. Any thoughts?

Chris.B

Chris,

Is it possible you were observing the effect of improved seeing while
the thin clouds were passing over? In some areas -- like here in
Southern California (I don't know about others) -- the conditions that
spawn the thin clouds also bring better seeing. In our case, it's low
clouds that form due to the proximity of the ocean. It may also be true
that the increase water content stabilizes the air. Could something
like this be responsible for the increased detail you're seeing? FWIW,
I've never noticed a color shift of any kind through thin clouds.

Mike Simmons

Mike Simmons wrote in message ...


Chris,

Is it possible you were observing the effect of improved seeing while
the thin clouds were passing over? In some areas -- like here in
Southern California (I don't know about others) -- the conditions that
spawn the thin clouds also bring better seeing. In our case, it's low
clouds that form due to the proximity of the ocean. It may also be true
that the increase water content stabilizes the air. Could something
like this be responsible for the increased detail you're seeing? FWIW,
I've never noticed a color shift of any kind through thin clouds.

Mike Simmons

It's not quite how I would describe it. The sudden arrival and
removal of detail in Jupiter's belts with each passing cloud was
immediately noticable. Starved as I was by pooor seeing over many
months of staring at Jupiter & Saturn at every opportunity. The fact
that I was seeing detail only in those fleeting moments is both
irritating and frustrating. It's not a form of filtration I can
recommend to other than a complete masochist. It was like trying to
see a detail in the landscape while looking through line-side trees
from a fast moving train. g

Chris.B

On 1 Aug 2003 12:40:58 -0700, (Chris.B) wrote:

It's not quite how I would describe it. The sudden arrival and
removal of detail in Jupiter's belts with each passing cloud was
immediately noticable.

I noticed the same thing while viewing Mars last week as the fog
rolled in. The decrease in brightness as a cloud passed in front of
the planet seemed to bring out some detail. Later in the night after
the fog passed I used the Sirius Optics NPC for a similar effect.

Al Hall