Starship Asterisk*

alter-ego wrote:

The Dawg wrote:

Guest wrote: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!

sOnIc wrote: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..."

owlice wrote: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

Chris Peterson wrote:

alter-ego wrote: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.

alter-ego wrote: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?

ronlevandoski wrote: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

Radarman wrote:
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

chadair wrote:
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...

alter-ego wrote:

ronlevandoski wrote: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."

sOnIc wrote: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

sOnIc wrote: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).

Radarman wrote: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.

geckzilla wrote: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.

Guest wrote: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.

Eric Bateman wrote: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.

chadair wrote: ....
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

owlice wrote:
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?

• Hoofbeats, horses.