APOD: Milky Way Over Abandoned Kilns (2011 Jul 25)

[sOnIc]

Sorry, just to justify my comment after reading the above explanation...

I would say the foreground Kiln images had a different sky which was removed with software, yes? I can see the 'terminator' or the edge where its not properly blended. The biggest give away is bright foreground area on the far-left which should have been removed if it was done manually; but I suspect this area is a relic of the previous background upon which the Kilns were originally photographed? The second image, the night sky, was then added behind to give the appearance of one shot?

If I am wrong I take it all back....?

Previous APODs show some amazing examples of how to image "the night sky with a terrestrial landscape" properly. http://apod.nasa.gov/apod/ap110606.html

I am not a grumpy old git that loves moaning, I'm a keen photographer myself and I use Photoshop professionally.

I've pointed out photoshop editing in astro images to people before and their reaction was "Ahh yea just like the moon hoax images..."

[edibleplantguy]

Easily the lowest quality image I remember from APOD. My brain does not like to point my eyes there, at all.

[Radarman]

The charcoal kilns are near Ely, Nevada in the Ward Charcoal Ovens State Historic Park. http://parks.nv.gov/images/wcoparkmap.jpg The ovens are oriented with the doors facing southward, east is toward the left. The snow-capped mountain could be in the Great Basin National Park. The source of the sky glow is probably Las Vegas.

You must be quite familiar with the Ward Ovens. I've lived in Nevada, but saw them. However, I have to differ with your conclusions. If the doors face south and the green glow is in the east (and a little to the north?) it can't be light polution from Las Vegas, for a few reasons: 1) it wouldn't be green; 2) it's some 250 miles away, half way across the state, too far below the horizon given the curvature of the earth; 3) Las Vegas is almost due south, not east or north east.

FYI, I have a few comments about this:
1. I've identified the camera location and headings for the APOD (within a few degrees). I estimate the FoV for the 6 kilns to be ≈70º
- Camera location : Lat≈ 39° 2'13.95"N; Long ≈ 114°50'51.51"W
- The small peak between kilns #2 and #3 is at an absolute heading ≈144º (0º = North, 90º = East)
- The green blob is at a heading ≈ 121º
2. Dawg, you are certainly right about Las Vegas not being the source of the green blob. It is at a heading ≈ 185º (almost due south) which puts in right behind kiln #1 (on the right), so it is
not possible to verify if it is visible in the APOD.
- One correction, Las Vegas is 200 miles from the kilns not 250.
- I have been to southern NV and could visually see sky glow from Vegas lights 130 miles away. Could this Vegas glow be photographed from the kiln location? Yes, according to Chad Moore.
3. Cedar City (pop. 28,000) is 135 miles away at a heading of 134º. Now, I don't believe that ground lighting can neccessarily be excluded ipso facto. We don't know the exact spectral content of the green glow, and we certainly know that many effects contribute to the color that we see in the image. It is clear in the APOD image blues and reds are enhanced from visual experience, and I've seen city light sky glow pictures that indicate a strong green component, e.g mercury vapor lighting. However, the APOD green glow is 10º further east from Cedar City, and expecting to see a city at 130 miles that is 1.4% the size of Vegas (and relatively much less lit!) does not add up.

I believe natural air glow is the best answer, assuming it can appear in discreet patches as it looks in the APOD.
I question aurora because I have never experienced an aurora (Seattle area) popping up on the southern horizon and no where else. I.e. aurora borealis activity "grows" from the north and migrates southward (every time in my experience). I keep track of the auroral oval (and the KP) and this trend is very strong. I can certainly believe seeing an aurora on the northern horizon, but not an isolated blip near the southern horizon. The auroral activity to the north is always very apparent if there is a visible zenith aurora. I believe if Tom did not see any broad-area auroral activity that night, the green glow is not a localized aurora in his picture (I also don't think this is an aurora australis either)

Tom - I've seen fantastic skys from dark locations in Washington, very dark skys in Nevada, and Australia. My opinion is your image, which is visually astounding, has exaggerated color balances which really help bring out the sky's beauty as you want to show, but are not directly experienced by eye. Maybe the image colors are all in the right proportion(?), but I don't trust the faint green glow as really being "green", at least not enough to preclude a ground light source, like a city or nearby well-lit farm. My criticism is meant to relate only to the details of the green glow, and not the quality of your work.
I think it's a great composition and I'm glad you submitted it!

You really did the homework on this one! And thanks for the supportive comments. I agree with the natural airglow theory as being the best, since most manmade sources can be ruled out (Area 51 isn't quite in the right direction either!). Unfortunately I was too busy taking the photo to notice the airglow visually. I checked the RAW file to verify the colors weren't shifted in processing - it is substantially green. Regarding the sky colors, I did not pump up the saturation; rather the histogam was stretched about 2x to improve contrast, I color balanced with some added blue to match my visual impression (the RAW histogram showed a predominant red), and local contrast was improved using Nik software. Far less PS CS5 work was done than what is normally done in virtually every astrophoto. However, I'm not sure why there is so much mauve/pink. It could be a combination of blue starlight and reds from various sources. I've also heard it's due to UV leaking into the cam's sensor. But it is a persistent, nearly dominant color in my Nevada night sky images.

Tom McEwan

[Radarman]

Sorry, just to justify my comment after reading the above explanation...

I would say the foreground Kiln images had a different sky which was removed with software, yes? I can see the 'terminator' or the edge where its not properly blended. The biggest give away is bright foreground area on the far-left which should have been removed if it was done manually; but I suspect this area is a relic of the previous background upon which the Kilns were originally photographed? The second image, the night sky, was then added behind to give the appearance of one shot?

If I am wrong I take it all back....?

Previous APODs show some amazing examples of how to image "the night sky with a terrestrial landscape" properly. http://apod.nasa.gov/apod/ap110606.html

I am not a grumpy old git that loves moaning, I'm a keen photographer myself and I use Photoshop professionally.

I've pointed out photoshop editing in astro images to people before and their reaction was "Ahh yea just like the moon hoax images..."

Yes, take it all back! I too am an avid photographer and I can alos see why some people doubt the image. I gave a detailed response to Ann that provides info on the photo that should answer some of your questions. What surprises me is how many people don't seem to know that a proper time exposure under starlight will produce a daytime-like image and with the sky as seen in my photo. Amazingly, the RAW histogram of the kilns/forground showed perfect color balance (maybe the red skyglow here in NV balanced what I would expect to be an otherwise blusih cast on the landscape). About the image quality, the original image is five 21MP frames and the center star trails are sharp. It looks great on a 20x30" print. However, APOD had to resize the image and it looks terribly blobby. Too many stars! Also it was very windy so all the veg is blurred. To top that off, I had to mask the sky during processing and that left a fine line that is hard to touch up. Nevertheless, the image has already won Grand Prize in a magazine photo contest. I'm starting to think this photo represents a winning photography technique. Tom McEwan

[sOnIc]

Hi Tom, I'm honestly not trying to discredit your work, but you haven't answered my question - "I would say the foreground Kiln images had a different sky which was removed with software, yes?"
So to confirm you are saying the kilns are not 'cut-out' from their original background? I find that incredibly hard to believe.

Where's the 'belt of Venus' effect? (The low band at the horizon where the stars should be fading out as a result of looking through much more atmosphere).

As for the bottom-left lighter patch of background, I just can't see 'moonlit hill' as explaining why this looks like a remnant of the original background, the edge looks far too defined; just like a rough Photoshop 'selection'.

If I'm wrong then I'll have to be careful in future, and this image has the effect of a dual layer Photoshop job; when it actually is not. Maybe its just 'unusual' lighting on that left most hill from the thin crescent Moon as you say, maybe your panorama software has made a mess of the fringe of the kilns as well as the complication of 75 secs of star movement between shots...

EDIT: Ahhhhh! "I had to mask the sky during processing and that left a fine line that is hard to touch up" .. you're saying you used a Photoshop mask to apply a different adjustment to the sky than to the foregound? If I've read you right then this explains everything?!? I'm sure this will be up for debate but that's not a 'winning photography technique', that is overuse of Photoshop to create an unreal impression (imo), and as you know I'm not the only person who spotted the un-natural outcome.

Either way, it is a beautiful foreground subject, and by sounds of it a wonderful place to do night sky imagery...

(BTW I have only just discovered panorama's myself by upgrading to the very latest Photoshop - very useful for NLC: http://www.flitemedia.com/photography/night-sky.php )

[alter-ego]

Info on airglow: http://www.atoptics.co.uk/highsky/airglow1.htm
http://www.atoptics.co.uk/highsky/airglow2.htm
http://www.atoptics.co.uk/fz378.htm

Thank you, Owlice, for the gentle reminder of that excellent website for atmospheric phenomena. I feel chagrined that I did not go there for this topic - it's so easy for me to put a set of blinders on.

[alter-ego]

I question aurora because I have never experienced an aurora (Seattle area) popping up on the southern horizon and no where else. I.e. aurora borealis activity "grows" from the north and migrates southward (every time in my experience). I keep track of the auroral oval (and the KP) and this trend is very strong. I can certainly believe seeing an aurora on the northern horizon, but not an isolated blip near the southern horizon.

I've photographed low-level auroras (too dim to be visible) all over the sky, including to the south. They tend to be diffuse streamers that can appear anywhere. So I have no reason to think this couldn't be a photographic aurora, even towards the south- especially given that a significant CME hit the Earth right around the time the picture was taken. Of course, skyglow is also a likely explanation, although atmospheric extinction makes such a strong band of skyglow so near the horizon unusual.

Very interesting - good input.
It doesn't surprise me that there could be faint, low-level "fringe" activity that might show up as random small streamers. I don't understand the EM behind this that allows pockets of threshold aurora to dribble through the magnetic field at lower latitudes in that manner and not show up in multiple areas. I'm thinking that Tom should play the lottery. To me, it still seems highly unusual (or lucky!) that a single, small auroral blob should be in that field of view, and at that latitude / altitude. I guess the time scale for dramatic auroral changes is on the scale of a single exposure so that if Tom had dedicated the entire evening making wide FoV sky exposures, it's possible multiple glowing regions might have been captured that night. Looks like we may not resolve this one for sure. However, your post convinces me that it is certainly possible. In any case, I'm going to investigate this further, I just wasn't aware that auroral activiity could be that subtle.

Having experienced and recorded these faint streamers, and being familiar with sky glow phenomena, do you have occasions where you aren't sure what type you're dealing with?
As with Tom's image, does a single captured event seem normal to you?
And one last question, how over the last 10 years, how many zenith auroras have you witnessed? I'm interested because I believe that, statistically, there should be more, and stronger, auroras were I am at the higher magnetic latitudes. Unfortunately, in western WA, there are a large number of cloudy evenings. ☺

[Chris Peterson]

Having experienced and recorded these faint streamers, and being familiar with sky glow phenomena, do you have occasions where you aren't sure what type you're dealing with?

All the time. Depending on the sort of structure I see and how it changes with time, the solar activity, and the position in the sky, I make some assumptions about whether I'm seeing skyglow or photographic aurora. But the key word here is "assumption".

As with Tom's image, does a single captured event seem normal to you?

Absolutely. Especially if this shot was made around June 4, I'd expect photographic auroras in Nevada.

And one last question, how over the last 10 years, how many zenith auroras have you witnessed?

Visually, eight or ten (from latitude 38.8°N). All were back in 2001-2004, when solar activity was high. Photographically, anytime the Kp gets up around 5 there's a good chance I'll see an elevated sky background, sometimes showing structure. Whether that is skyglow or actual aurora I don't know. I think that low level auroras essentially become part of skyglow under some conditions. Certainly, those of us who carefully monitor the sky background have to disinguish between solar max and solar min measurements. Around solar max my zenithal sky background averages 20.9 mag/arcsec^2, and that darkens to 21.3 mag/arcsec^2 during solar min.

[ronlevandoski]

Hello everyone.

I am a good friend of Tom McEwan. I have seen the original star lit kiln images he has hanging in his lab and I can tell you that the original image has tremendous impact, excellent technically and you just cannot take your eyes off of it from across a twenty foot room.

My wife is a judge for our camera club here in southern Nevada. She agrees that this is an outstanding image. The artifacts, blurriness, etc., are no at all present in the original 18X30 (approximately) prints that I examined.

I have had a chance to do photography with Tom and his imaging, artistry and processing abilities are absoulutely first rate.

I have taken similar images at the Race Track in Death Valley with a very thin moon illuminating the mountains to the east with a similar effect. Great Milky Way with mountains looking nearly like daylight. Very little Pshop to get the image presentable.

Get your digital camera and a tripod and get out there and get some images. This is a whole new area for photographers.

Congratulations. Great job Tom!

docron

[alter-ego]

Hello everyone.

I am a good friend of Tom McEwan. I have seen the original star lit kiln images he has hanging in his lab and I can tell you that the original image has tremendous impact, excellent technically and you just cannot take your eyes off of it from across a twenty foot room.

My wife is a judge for our camera club here in southern Nevada. She agrees that this is an outstanding image. The artifacts, blurriness, etc., are no at all present in the original 18X30 (approximately) prints that I examined.

I have had a chance to do photography with Tom and his imaging, artistry and processing abilities are absoulutely first rate.

I have taken similar images at the Race Track in Death Valley with a very thin moon illuminating the mountains to the east with a similar effect. Great Milky Way with mountains looking nearly like daylight. Very little Pshop to get the image presentable.

Get your digital camera and a tripod and get out there and get some images. This is a whole new area for photographers.

Congratulations. Great job Tom!

docron

Nice contribution!
It's too bad that the APOD presentation degraded the image, but, even so, not very many catch my eye like Tom's - I'd love to see the image as quality print. Despite APOD's imperfections, I'd like to point out what I like about it. Particularly I like diversity of the APODs. The pictures reflect the diversity of people, talent and equipment involved. From the high-end professional to a drink can pinhole camera. Literally anyone can contribute. Depending on creativity, simplicity, technical prowess, (it goes on), there is a place for new and different pictures. I personally enjoy pictures like Tom's because they bring an air of freshness to the experience. Like you say: "..get out there and get some images." I'll add to that: Submit them and you have a chance at the world seeing them.

"The APOD archive contains the largest collection of annotated astronomical images on the internet."

[candersen]

Carl, I have also asked this of Chad, above. When I shot the photo, a thin moon still illuminated the distant mountain to the east (the white patch on the left in the photo) while the kilns were in a shadow from a nearby hioll to the west. The green mist area was most likely still moonlit. What is your opinion that it might be a reflection effect? Thanks, Tom McEwan

I would tend to agree with what Chad said above. I would be surprised if reflected moonlight were to manifest itself in a way which appears to be both reasonably monochromatic and at or very close to the 5577 aurora/airlgow line, but short of seeing an actual spectra, I guess you could never be 100% sure. Qualitatively, it also just seems a little dim to be moonlit clouds. A very rough gauge I use for estimating brightnesses is that the Milky Way is on the order of 1 kiloRayleigh, moonlit thin cirrus are on the order of 10 kR and moonlit cumulus are on the order of 100 kR.

As to the aurora vs. airglow question, I took a quick look through the archived Kp data at http://www.swpc.noaa.gov/ and found two periods of Kp > 4, one from 18:00 UT on 6/4 through 3:00 UT on 6/5 and a second from 0:00 to 3:00 UT on 6/8 and it is significantly more likely that a faint aurora would be observable in Nevada during one of these periods than during a period of lower Kp.

I have seen some really weird stuff above distant lighting storms at night- flashes of green and blue, but I'm not familiar with the physics. But maybe...

You might have been seeing some stratosphere/mesosphere lightening-related phenomena such as Sprites, Jets or Elves. I believe they are generally thought to be red and/or blue and tend to be very short lived (down to a ms or so) but can be quite bright. I am not aware of any reports of these showing up as straight-green but these phenomena are not yet completely understood, so who knows...

[Radarman]

Hello everyone.

I am a good friend of Tom McEwan. I have seen the original star lit kiln images he has hanging in his lab and I can tell you that the original image has tremendous impact, excellent technically and you just cannot take your eyes off of it from across a twenty foot room.

My wife is a judge for our camera club here in southern Nevada. She agrees that this is an outstanding image. The artifacts, blurriness, etc., are no at all present in the original 18X30 (approximately) prints that I examined.

I have had a chance to do photography with Tom and his imaging, artistry and processing abilities are absoulutely first rate.

I have taken similar images at the Race Track in Death Valley with a very thin moon illuminating the mountains to the east with a similar effect. Great Milky Way with mountains looking nearly like daylight. Very little Pshop to get the image presentable.

Get your digital camera and a tripod and get out there and get some images. This is a whole new area for photographers.

Congratulations. Great job Tom!

docron

Nice contribution!
It's too bad that the APOD presentation degraded the image, but, even so, not very many catch my eye like Tom's - I'd love to see the image as quality print. Despite APOD's imperfections, I'd like to point out what I like about it. Particularly I like diversity of the APODs. The pictures reflect the diversity of people, talent and equipment involved. From the high-end professional to a drink can pinhole camera. Literally anyone can contribute. Depending on creativity, simplicity, technical prowess, (it goes on), there is a place for new and different pictures. I personally enjoy pictures like Tom's because they bring an air of freshness to the experience. Like you say: "..get out there and get some images." I'll add to that: Submit them and you have a chance at the world seeing them.

"The APOD archive contains the largest collection of annotated astronomical images on the internet."

POOR IMAGE QUALITY

When I shot the kilns as a panoramic, the image size from 5 stitched 21MP images was 103MP. This image won the Grand Prize in a magazine photo contest, and the art editor insisted it be sharp enough for a 2 page spread at 300DPI. It was. Yet when I looked at the APOD image I was shocked at the poor quality. No wonder there were so many negative responses about poor quality. Quite frankly, I'm embarassed to tell friends about the APOD selection.

Here's what I found that I think APOD is doing wrong. When downsizing images in PS, there's a selection in the image size window labelled "bicubic sharper (best for reduction)." If you use this you will find the reduction to 1200 dpi produces sharp jaggies everywhere on my image, and not the soft out of focus image you presented. Secondly, many viewers have 1920 dpi monitors so a 1200 dpi image further degrades on full screen viewing. If you downsize to 1920 dpi using bicubic sharper and then save the jpg as a low quality image to stay near 200kB image size you will see that the result is significantly sharper than what you're presenting. I find it inexplicable that APOD staff would miss this and possibly degrade every image presented, so I can only assume there are other reasons for your processing techniques.

Tom McEwan

[sOnIc]

Hi Tom, I know the re-sampling problem you mean but this is not the issue and I cannot fault APODs jpeg processing, looking back through you will find lots of very sharp images.

The concept behind your image is excellent; its a fantastic scene, and obviously a superb location to photograph the night sky

The problem is one partially of post-processing, but also I suspect the original photography as well, please let me explain:

Look at this APOD in comparisson with your picture - the difference is quite remarkable.
Bobak's image looks wonderfully natural, its in the middle of the night and you can see that; though the milky way is awesomely bright and the foreground is clear and well visible.
Now if you look back at your image the difference is easily apparent, firstly your night sky looks over-saturated and overdone on the 'levels' type tools, the stars do also look blurry here and this might be a resizing problem but I'd have to see the original raw images to know, I suspect its actually an effect of the stars trailing. Secondly the foreground kilns leap out having the appearance of being overlaid; that is the reason I thought it was a 2 layer image at first, but it kind of is; you have pointed out that you masked the foreground to apply different treatments to it and this explains the unnatural effect which 'troubles' the mind, and again judging by the left most white patch you have used a LOT of extra brightening?

With 75 second shots you have significant trails, I'd either go for a long trail; or no trail. Also, even with a modern digital camera ISO 3200 sounds like a big compromise on quality?! I'd say you have over-exposed the original images? The brightest part of the Milky Way (Sag star cloud?) for example is actually blown out; clipped, if you look at Bobak's image it has plenty detail to that cloud. Myself I'd probably try 30 sec images at ISO 800 or something, and I bet Bobak's exposures were something like that? Then if you think the kilns are not showing up enough, perhaps silhouetted, remember that most foregrounds in images like this are illuminated by something; camp fires, flashlights, car headlights etc, sometimes natural or sometimes deliberately by the photographer, but ultimately not with Photoshop masking!

Would you not agree that you could do these exposures again and do it better? Or do you think you have the perfect image?
Whatever you think now; my bet is in a few years time you will look back on this image and realise that these points are indeed worthy of consideration.

I don't wish to present myself like a "know it all"! But I have some experience, and courage in my convictions...
Keep up the good work...
Chris

Some wonderful APODs working on the same technique: 1 / 2 / 3 / 4 / 5

[Radarman]

Hi Tom, I know the re-sampling problem you mean but this is not the issue and I cannot fault APODs jpeg processing, looking back through you will find lots of very sharp images.

The concept behind your image is excellent; its a fantastic scene, and obviously a superb location to photograph the night sky

The problem is one partially of post-processing, but also I suspect the original photography as well, please let me explain:

Look at this APOD in comparisson with your picture - the difference is quite remarkable.
Bobak's image looks wonderfully natural, its in the middle of the night and you can see that; though the milky way is awesomely bright and the foreground is clear and well visible.
Now if you look back at your image the difference is easily apparent, firstly your night sky looks over-saturated and overdone on the 'levels' type tools, the stars do also look blurry here and this might be a resizing problem but I'd have to see the original raw images to know, I suspect its actually an effect of the stars trailing. Secondly the foreground kilns leap out having the appearance of being overlaid; that is the reason I thought it was a 2 layer image at first, but it kind of is; you have pointed out that you masked the foreground to apply different treatments to it and this explains the unnatural effect which 'troubles' the mind, and again judging by the left most white patch you have used a LOT of extra brightening?

With 75 second shots you have significant trails, I'd either go for a long trail; or no trail. Also, even with a modern digital camera ISO 3200 sounds like a big compromise on quality?! I'd say you have over-exposed the original images? The brightest part of the Milky Way (Sag star cloud?) for example is actually blown out; clipped, if you look at Bobak's image it has plenty detail to that cloud. Myself I'd probably try 30 sec images at ISO 800 or something, and I bet Bobak's exposures were something like that? Then if you think the kilns are not showing up enough, perhaps silhouetted, remember that most foregrounds in images like this are illuminated by something; camp fires, flashlights, car headlights etc, sometimes natural or sometimes deliberately by the photographer, but ultimately not with Photoshop masking!

Would you not agree that you could do these exposures again and do it better? Or do you think you have the perfect image?
Whatever you think now; my bet is in a few years time you will look back on this image and realise that these points are indeed worthy of consideration.

I don't wish to present myself like a "know it all"! But I have some experience, and courage in my convictions...
Keep up the good work...
Chris

Some wonderful APODs working on the same technique: 1 / 2 / 3 / 4 / 5

Chris,

Thanks for the nice, detailed response. Star trailing and bloat indeed detract from the image. Next time things will be better!

ISO 3200 is actually a non-problem. Nik DFine software and shooting panoramics, where the effective ISO is divided by the number of frames in the image (5), work wonders.

I disagree with a "conformist" view that night shots should look mostly dark. That’s not the case with some animals or with modern cameras. The APODs you gave links to are great images but they’re underexposed with respect to the foreground. Hence the silhouettes.

My image is deliberately processed bright so the viewer can see a colorful, energetic and majestic night sky in full context with a “daylight” terrestrial scene. How things might look at night if we had really good eyes and no light pollution. I will suggest this descriptive phrase next time (hopefully there is one) to help the viewer understand the “why” behind the brightness levels.

Tom McEwan

[sOnIc]

Fair enough Tom : ) Again I'm sorry if all this has detracted from the praise which you are deservedly getting for this image.
I'm really hard on myself with photography, always finding fault with my images and preparing to fix them on the next attempt, that's the 'motivation' I guess.
Congrats on that award and all the best for the future ...
Chris

[geckzilla]

Something occurred to me about this image that I did not originally consider. This was very likely submitted to APOD in the same format as would be submitted to a printer. It is common to adjust dark (read as: lots of ink) images to compensate for something known as dot gain. Result: It looks like crap on your computer screen but looks great once the printer outputs it. Could be what happened, here.

[Indigo_Sunrise]

Where's the 'belt of Venus' effect? (The low band at the horizon where the stars should be fading out as a result of looking through much more atmosphere).

That's not quite what the Belt of Venus refers to. See here.

About the image quality, the original image is five 21MP frames and the center star trails are sharp. It looks great on a 20x30" print.

I'd love to see that!

[Case]

Something occurred to me about this image that I did not originally consider. This was very likely submitted to APOD in the same format as would be submitted to a printer. It is common to adjust dark (read as: lots of ink) images to compensate for something known as dot gain. Result: It looks like crap on your computer screen but looks great once the printer outputs it. Could be what happened, here.

The click-through high res image (3600x1800 px) has a color profile Adobe RGB, which has a wide color gamut and works well with 'warm' colors like red and yellow. The presented embedded image (1200x600 px) has the color profile removed, without profile conversion. This results in viewers and browsers showing the image as sRGB (web default), which has a smaller color gamut (but still works quite well with greens and unsaturated colors). This profile mismatch make the image rather dull. We see the reds and yellows less saturated compared to what was intended.
If you combine this with a sharpened downsample (as Tom suggested in post 153718), then you'll get the comparison shown below. On the left as I believe it was intended, and on the right as shown in the APOD page.


Two suggestions (this has been mention before) to the APOD editors:
- Do not remove color profiles, so that users of color profile aware browsers see images as intended.
- If you must remove profiles or otherwise feel a need for sRGB standard, then do a color profile conversion first, for a best possible match in the other color space.

Color management and working with color profiles may not be easy, but this once again shows that it is important to get it correct.

[Eric Bateman]

The charcoal kilns are near Ely, Nevada in the Ward Charcoal Ovens State Historic Park. http://parks.nv.gov/images/wcoparkmap.jpg The ovens are oriented with the doors facing southward, east is toward the left. The snow-capped mountain could be in the Great Basin National Park. The source of the sky glow is probably Las Vegas.

The photo's view is the wrong direction for the snow-capped mountain to be in Great Basin National Park. GBNP is to the east, but you can't see it from the kilns, anyway. The photo's view is generally south, which rules out the aurora borealis, as someone else suggested. When I saw the photo, I suspected the green glow was from Las Vegas. Ward Charcoal Kilns are far enough that the city's glow wouldn't be visible with the naked eye, but on a time exposure it might show up. The brightest light in Las Vegas is green, and shines out of the top of the Luxor Hotel.

[alter-ego]

The photo's view is generally south, which rules out the aurora borealis, as someone else suggested.

Not necessarily so. Low-level, photographic aurora is more subtle, and since aurora activity was apparently high during this time, it is reasonable to expect low-level activity occurring at lower latitudes
http://asterisk.apod.com/viewtopic.php? ... 25#p153578

When I saw the photo, I suspected the green glow was from Las Vegas. Ward Charcoal Kilns are far enough that the city's glow wouldn't be visible with the naked eye, but on a time exposure it might show up. The brightest light in Las Vegas is green, and shines out of the top of the Luxor Hotel.

1. I believe any Las Vegas glow is behind kiln #1 (right side) http://asterisk.apod.com/viewtopic.php? ... 25#p153551
2. Vegas glow is visible as far away as 210 miles http://asterisk.apod.com/viewtopic.php? ... 25#p153544
3. The large glowing region in the picture is not from a single hotel, let alone a vertically directed beam (which I think you're referring to). Also, as I said, Vegas is not in that direction anyway.

....
As the scientist from Fairbanks indicated (and they know their aeronomy) it could very well be aurora. Since aurora reach up hundreds of KM into the atmosphere, you could very well see it near the horizon from modest latitudes like 35 degrees N in the US.

I don't think it is moon reflection. Moonlight is basically sunlight skewed a little to the blue in color. Both forward scattering and backscattering of moonlight should be yellowish in color.

I have seen some really weird stuff above distant lighting storms at night- flashes of green and blue, but I'm not familiar with the physics. But maybe...

Chad Moore
National Park Service

PS. Las Vegas light pollution is visible from 210 miles, but it tends to be sodium-colored (yellow) at that distance

I hope this helps ☺

[owlice]

Airglow.

[neufer]

Airglow.

• Owlice: I just want to say one word to you. Just one word.
  
  Neufer: Yes, ma'am.
  
  Owlice: Are you listening?
  
  Neufer: Yes, I am.
  
  Owlice: Airglow.
  
  Neufer: Exactly how do you mean?

[owlice]

• Hoofbeats, horses.

[kristalleonard]

HI,
I have a similar glow in this photo that I also took in July this year. This is from a dome in Yosemite National Park, CA where I was at 9000ft elevation. The photo is a 5 minute exposure, minor curves adjustment in post processing. You are looking NE (mostly north) so the green bands appear to be radiating from the east--coincidently where Nevada would be (the Kiln photo was also taken in Nevada in July) I shot this on July 7, 2011, about 1am. I always assumed (and hoped) it was auroras, so it is is interesting to see another night photo from July with the green glow as well.

http://www.facebook.com/Yosemitephoto#! ... =1&theater

[Keith Millsap]

This is an old tread but I thought I'd chime in. I'm from Central California and I've only seen an Aurora once. That was early June of 1980 about 60 miles SW of Ely near Duckwater while mapping for my Senior thesis. The sky for about 30 degrees above the northern horizon was pulsing and glowing green. The only other astrological phenomenon close to that was the comet in the late 90's. Coming back from Kent, Washington we pulled off i5 near Mt Shasta and the tail of that badboy stretched across 2/3 of NE sky.