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Can we talk about the color of the night sky where you are?

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#1 Star-gaze69

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Posted 16 August 2014 - 06:06 PM

My backyard in SE Texas is supposedly in a Yellow Zone, which should give me a telescopic image of bright pinpoint stars on a black background. Unfortunately, many (most?) times those stars are on a gray background. Do you have a background like that where you are? Is this due to sky brightness? High clouds? Would filters help to darken the sky image?



#2 17.5Dob

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Posted 16 August 2014 - 06:29 PM

My backyard in SE Texas is supposedly in a Yellow Zone, which should give me a telescopic image of bright pinpoint stars on a black background. Unfortunately, many (most?) times those stars are on a gray background. Do you have a background like that where you are? Is this due to sky brightness? High clouds? Would filters help to darken the sky image?

 

What size scope and what magnification do you use ? Even in grey/ black zones, the pitch black edge of my eyepiece FOV is always very distinct from the darker grey in any of my 'scopes at the lower end of magnification. Likewise, kick up your magnifiation to 40X inch and and even from downtown New York City, the background will be black.

BTW, yellow is still "pretty bad" for any type of low power viewing without some sort of LP filter. Have you considered trying an LP/ UHC filter ? What type of objects to mainly observe ?


Edited by 17.5Dob, 16 August 2014 - 06:30 PM.


#3 amicus sidera

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Posted 16 August 2014 - 06:46 PM

What size scope and what magnification do you use ? Even in grey/ black zones, the pitch black edge of my eyepiece FOV is always very distinct from the darker grey in any of my 'scopes at the lower end of magnification. Likewise, kick up your magnifiation to 40X inch and and even from downtown New York City, the background will be black.

BTW, yellow is still "pretty bad" for any type of low power viewing without some sort of LP filter. Have you considered trying an LP/ UHC filter ? What type of objects to mainly observe ?

 

 

Yup, increasing magnification works wonders in giving a more pleasing, darker sky background, although extended objects tend to fade away as magnification increases. If you are in a yellow zone, try for deep sky on those evenings when a frontal passage has left the air as dry as possible; scattering of light is reduced and thus light pollution is often markedly diminished under such conditions. Here in NJ, under red-bordering-white-zone skies, a very dry atmosphere often adds as much as a full magnitude to the  zenithal limit.



#4 GlennLeDrew

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Posted 16 August 2014 - 07:31 PM

Even from above the atmosphere the sky is not 'black', due to sunlight scattered by interplanetary dust. The best ground level sites are about 1.5 magnitudes brighter at the zenith, due mostly to natural airglow at about 100km altitude. This sky light is some 15 times brighter than the light from stars down to 6.5 magnitude, and makes walking about without a flashlight no problem. The worst light polluted skies are a good 5 magnitudes, or 100 times brighter still.


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#5 NorthWolf

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Posted 16 August 2014 - 07:46 PM

You get grey skies in the summer months also due to twilight.

#6 youngamateur42

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Posted 16 August 2014 - 08:08 PM

Of course, viewing objects not near the zenith will also cause a gray background.  It actually can vary quite a bit.  Some nights, even viewing directly overhead produces an annoying amount of background light.  During the winter months, it's almost always clearer than in the summer.



#7 NorthWolf

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Posted 16 August 2014 - 10:29 PM

Yeah big time, I remember some nights I just wanted to pack the dob but than as the night goes on it gets darker, during the summer the best hours are from 12-3 am around! By the way you are lucky to live in a yellow zone op, I live in on the border of a white-red zone and have still had fantastic views in all seasons.



#8 sparkyht

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Posted 17 August 2014 - 06:42 AM

From the middle of a white zone I have a salmon HPS-driven glow in every horizon, fading to a grayish-white glow to the zenith. The smoke from the fires in Canada and the weather pattern for the last 3 months has brought a haze that makes it even worse.

 

It's hideous, I tell you.



#9 GlennLeDrew

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Posted 17 August 2014 - 08:29 AM

According to the light pollution map my apartment in west Ottawa is inside a red zone (the outer of the two shades.) Yet on a decent night when the troposphere is clean I see stars to at least 5.5m. Indeed, on one particularly clear night I glimpsed the 'Central America' portion of the North America nebula with an unfiltered 10X50 bino. From my horribly lit-up balcony (by over a dozen nasty 'cobra head' streetlights)! I used a hood to block all extraneous light, and hunkered down behind the solid panel at the railing.

 

The North America unfiltered from a red zone? I gather the common concensus would say, "nyet." Needless to say, I treat the light pollution map with some circumspection.


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#10 obin robinson

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Posted 17 August 2014 - 10:15 AM

The northern sky here is dark brown. The southeast is greyish-blue. The are directly overhead and to the southwest is sometimes dark blue and sometimes dark blueish-grey. None of it is black. One night I actually counted the number of stars overhead and it was less than 100 visible to the naked eye.

 

obin :(



#11 csrlice12

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Posted 17 August 2014 - 10:56 AM

I'll get back with you once the clouds go away...... :lol:

 

Was out last night (White Zone), there's a lake/park close by and it's the only "dark" area around.  I had cleaned my mirror and did some tweeking of the dob earlier in the day, added a cooling fan, and wanted to try it out...why, oh why didnt I just listen to the voice in my head that told me to go to the dark site........everything was working well, the sky was clear, I had a Warp factor of 0.2 and everything I told the controller to go to was right there in the fov, didn't even need a finder.....of course everything was washed out....but, at least the scope works!!  Yea, in town its all grey in the eyepiece.....



#12 Star-gaze69

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Posted 17 August 2014 - 01:11 PM

The northern sky here is dark brown. The southeast is greyish-blue. The are directly overhead and to the southwest is sometimes dark blue and sometimes dark blueish-grey. None of it is black. One night I actually counted the number of stars overhead and it was less than 100 visible to the naked eye.

 

obin :(

 Out here in Waller County, my NexStar has stayed in its resting spot unused due to poor seeing conditions. One day last week I counted 7 stars visible at 12 midnight. It has been this way ALL summer long! I long for the cold, crisp nights of winter.

 Gary  :(



#13 chaoscosmos

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Posted 17 August 2014 - 02:20 PM

Strange, I just noticed last night this specific issue.  That the sky was different colors in different directions, to the point where my first thought was something strange must be going on.  I'm sure I knew this but don't know that it's ever been so obvious before.

Might have something to do with the fact it was the first time in several months I've had the scope out to take a look at things.



#14 jgraham

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Posted 17 August 2014 - 02:21 PM

I observe from a solid red zone. Visually my sky is a soupy gray. Photographically it is a soupy red. A good imaging sky glow filter or the Baader semi-Apo filter helps a smidge visually and quite a bit photographically.



#15 ylem

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Posted 17 August 2014 - 08:01 PM

To the east Target uses orange lights, to the south the car dealers use white,  to the north the city lights are grey, tlo the west it's black because of heavy foliage. in the winter the west is bright white do to bright yard and farm lights. 


Edited by ylem, 17 August 2014 - 08:17 PM.


#16 NorthWolf

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Posted 17 August 2014 - 09:08 PM

This picture says it all:

 

http://upload.wikime...egories.svg.png

 

Study twilight hours in your area. Summer is almost over though. Worst month is July for many people.



#17 Jon_Doh

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Posted 18 August 2014 - 08:39 AM

My sky is gray and none of the Milky Way is visible.



#18 Tony Flanders

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Posted 18 August 2014 - 09:03 AM

My backyard in SE Texas is supposedly in a Yellow Zone, which should give me a telescopic image of bright pinpoint stars on a black background.


Pinpoint is a matter of seeing, not skyglow. If anything, stars look more like pinpoints when the background is bright.

As for the background, at wide-open exit pupils -- say 4 mm and bigger -- even a sky with zero light pollution is quite bright. You should have no trouble seeing the field stop as a black circle around a gray field.

And the yellow zone is very far from having zero light pollution. Although it's extremely dark by suburban standards, artificial skyglow is stronger than natural skyglow across the entire sky in the yellow zone, and much stronger near the horizon.

Would filters help to darken the sky image?


Yes, and everything else too. Unless you're viewing nebulae through a nebula filter, filters will make the view worse overall.

High magnification is your best weapon against skyglow. At a 0.5-mm exit pupil, even a yellow-zone sky looks nearly black.

#19 REC

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Posted 18 August 2014 - 10:11 AM

I'm in a red zone with a light dome to the east. For those targets, I wait until they are at least 45* up in the sky.  I use a nebula filter for those objects and for other general objects I sometimes use a Baader Moon & Skyglow filter, helps some.



#20 sedmondson

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Posted 18 August 2014 - 05:49 PM

When we moved 20 miles from town to the middle of a yellow zone about 5 years ago, I thought how nice it would be to have dark skies. Now I notice how bright the sky is. Its not that the LP has gotten worse here, its just that I notice how bright the yellow zone really is. Its all relative. Someone living in the suburbs would love to be yellow; someone in yellow wants to be green (or how about blue). I think it seems darker if you can situate yourself such that there are trees surrounding you and blocking the sky up to 30 degrees or so. Then you can't see how murky the sky becomes as it approaches the horizon.



#21 Glen A W

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Posted 18 August 2014 - 06:07 PM

There is no such thing as a dark black sky, in my experience.  My sky is better than mag 6.5 across most of it, and I can see all sorts of dark clouds and breaks in the Milky Way.  The coathanger is often visible as individual stars to the naked eye.  But, the sky is not even close to black.  Through a scope at low power, the background is usually a surprisingly bright gray, especially anywhere near the Milky Way.  But with a little power, globular clusters just burst open, full of stars!  When observing from such a dark zone, I am much more aware of how twilight and the zodiacal light impact the sky brightness, as well.  I can see twilight in the northwest after Sunset for much longer than you'd imagine, considering my moderate 39N latitude.  There may be other auroral and skyglow types of issues, not to mention varying transparency, which is very apparent from such a dark sky.  The overall color of the sky here is a sort of dark blue, not black.

 

Glen


Edited by Glen A W, 18 August 2014 - 06:11 PM.


#22 NorthWolf

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Posted 18 August 2014 - 09:05 PM

Wow im currently out camping in a green blue zone...this is how it should be! I can see perhaps 1000 stars in my binocular view.

Edited by NorthWolf, 18 August 2014 - 09:05 PM.

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#23 Feidb

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Posted 18 August 2014 - 10:27 PM

Light gray, close to white most nights. It darkens slightly to the east, just enough to pick out some of the mag. 4 stars, maybe 4.5 on occasion. I have to go out of town to really see much, thought on occasion, I've been successful when I can know exactly where to look. Usually too bright to see my green laser pointer.



#24 cpper

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Posted 19 August 2014 - 12:04 PM

Dark brown last night here, in orange zone. The Milky Way was detectable, NELM was 5.5.



#25 Dennis_S253

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Posted 19 August 2014 - 02:05 PM

I'm not exactly sure how to answer your question but, The last two nights here were the best I have seen in months. The Milky Way was clearly visible from Scorpio to Cassiopeia. That is until the moon came up around 2:45 or so. Usually here in Florida at this time of year the water vapor is what kills the night sky. That's why I usually view from late September to mid May. Other than that it's just the Moon and Planets except on exceptional nights.






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