Big Sky Panorama

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Big Sky Panorama

Postby Jerry » Tue May 10, 2011 3:13 am

This site is pretty incredible. A guy traveled around the world to photograph the sky to create this panorama. 37000 images he took!

http://media.skysurvey.org/interactive360/index.html
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Re: Big Sky Panorama

Postby Doug Coulter » Tue May 10, 2011 10:08 am

He obviously does very nice work and earned any praise he got for this -- you're right, it's gorgeous! While having no where near the rez, I can almost see things like this with the NV device on a typical clear night out here -- it's nice for wide-field viewing, but an icky green. It's like there's no place you can point the thing and see black -- the sky is just full of stars in all directions. More in some than others, but like this -- no empty places at all.

Another panorama I've seen and like is one that added doppler info to this, and made a 3-d map of space -- reconstructed with plotting software. The universe in that one looks for all the world like a bunch of soap bubbles or beer foam with all the light emitting stuff on their surfaces. In that there are voids between the clusters -- but it's funny how round most of those voids are with all the "stuff" on their surfaces. If I were a cosmologist, I'd be thinking real hard about that one -- was Guth really right, and those are quantum fluctuations expanded along with space in the initial inflation? Quite a ratio in that case.
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Re: Big Sky Panorama

Postby chrismb » Wed May 11, 2011 5:22 pm

That is a very impressive display. At least it'll help me describe the milky way to my urban-bound young boys who've never really seen it. Even in the countryside here in UK you still don't quite get the spectacular of it like you do in *really* isolated places.

On the subject of panoramas, whaddaya think of this sunset panorama, then? I bet this guy never took a picture like this, in his travels!...

Image
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Re: Big Sky Panorama

Postby Doug Coulter » Thu May 12, 2011 10:55 am

That's pretty wild, Chris. Usually there's a lot of red in those. Where was this taken? We have so many nice sunsets here I've almost become immune to them. Of course, the really striking ones I always see while driving someplace without my camera in tow, I'll have to change that habit. I'm lucky to live in a place that's very visually pleasing and should share it (or boast?).

I've noticed a male/female dichotomy on this one. When I go out with a camera, I get all these pretty pictures (to me) of landscapes, things, places, wildlife, flowers. When my wife (any of them -- I've been around the block a time or few) go out with a camera what comes back is pictures of people.

A really neat thing to do with a large 'scope is get detailed pix of the nearest star, the one that's up when you're awake. I've used mine that way and it's a lot of fun. You can't of course just point a 10" scope at the sun, pretty likely something would burn (might be useful for that...if you could get it lined up first so the "beam" wouldn't hit black stuff in there and all come out). What I did was make a cover plate for the big thing out of cardboard (metal would be better but this was quick and dirty). I punched 4 roughly 1" holes in it around the perimeter, and put filters from those cheap glasses they sell for eclipse watching over them. Then you can point it at the sun and not be totally blinded by it - and retain the effect of a large aperture on resolution fairly well. There's actually quite a lot to see doing that, without even a fancy filter. But the pix with filters are stunning.

Of course, this isn't a slick as having those two-stage single H line filters they used to sell for about $8k...what those did was one for over the aperature would bandpass a fairly wide band in the red, and be somewhat also neutral density to cut the light down some. Then a very fancy filter at the eyepiece could not only select a single H line, but was so narrow it could "see" the doppler of H moving towards you vs away from you, and was tunable (in fact, the issue was IIRC that it would drift and needed tuning to be stable). This let you, in effect, see into the sun, not just the surface. NASA has some in space that have bands up to the deep UV for that, and their pix are really nice.

http://sohowww.nascom.nasa.gov/home.html

It turns out the sun is "ringing" at about 10^7 harmonically related frequencies (literally DC to daylight), and a photodiode put in the prime focus pointed at one of the little pockets of vibration can pick this up -- truly the music of the spheres. You don't get a good signal everywhere -- there are peaks and nodes. In other words, you don't see this in a signal from the whole sky -- it averages out.

Now, somebody like Jerry or Joe could contrive to make such a filter (it's all sputtering IIRC)....maybe even for sale. Real sharp filters could have significant uses in fusor diagnostics. Hint.

I believe it's just a ton of different dielectric layers. To get a real narrow one you have to have pretty tight control over all the layer thicknesses. I don't *think* you can get that as well with a diffraction grating, but I could be wrong. Now THAT, I understand is the ultimate challenge for a machinist, much like Chris comment much earlier about "how do you get the first screw threads". It seems to require excellent mechanical design and construction, then some very good realtime feedback as the grooves are cut perhaps using a short wavelength laser interferometer. Tight temperature control is also needed.

I haven't seen it mentioned in optics (I'm no expert), but in regular filter design there are various topologies to get what you want. You might have a bandpass section with a notch filter on either side to sharpen it up right around the bandpass, for example, and there are a ton of possible tricks.
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Re: Big Sky Panorama

Postby chrismb » Thu May 12, 2011 11:57 am

Doug Coulter wrote:That's pretty wild, Chris. Usually there's a lot of red in those. Where was this taken?
Gustev crater. ;)


Doug Coulter wrote:I've noticed a male/female dichotomy on this one. When I go out with a camera, I get all these pretty pictures (to me) of landscapes, things, places, wildlife, flowers. When my wife (any of them -- I've been around the block a time or few) go out with a camera what comes back is pictures of people.
It's an Asperger thing, a congential state of engineers...
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Re: Big Sky Panorama

Postby Doug Coulter » Thu May 12, 2011 12:47 pm

Ah, so I'm in a bad place to do such a survey -- being an engineer and mostly hanging with other ones. You might be right!
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Re: Big Sky Panorama

Postby Jerry » Thu May 12, 2011 9:31 pm

Meade sells a scope for solar viewing. Not cheap...

http://www.meade.com/product_pages/coro ... ronado.php
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Re: Big Sky Panorama

Postby Doug Coulter » Thu May 12, 2011 10:46 pm

Ah, it appears they bought Coronado, and yeah, unless something changed since, they're way not cheap. That was one nice little refractor according to the users reports (whether those were shilling or astroturfing I couldn't say). But I think the big scope can do a better job with the filters, like I did it (I never got the narrowband eyepiece one). There's just no substitute for size in basically diffraction-limited optics. Seeing can be really good going straight up in the daytime -- I didn't notice it being super bad anyway. You still have the couple hundred hz flutter from cells in the jet stream if you're under it, no matter what. But your eye seems to handle that well (better than a camera). Which is why I went with the video camera idea so I could simply ditch frames where it was bad and keep the rest.

At any rate, yeah, I had you in mind on those filters, since you were working up an accurate sputtering ability. I know of nothing else higher value-added, and there's basically no competition in that field I'm aware of. Not sure how that's advanced since I was into it, but then you had to temperature control the filters to tune them...Wonder why they went for just that one line too, maybe some other H line would be better for some things. NASA seems to think so. I understand why they don't do UV from the ground of course.

Seems to me that since the shorter wavelengths are more affected by seeing, and it's linear with wavelength, that you could have a multi-wavelength scheme that used the distortion of one to predict/correct another, too. That would need a color camera, which I never fooled with much outside the board-type vid cameras you can get cheap. The downside of them is mainly that you can't manually control the exposure, and the auto stuff in them really messes up on bright points. They were only good when you were looking at a planet and keeping the FOV completely on the planet so the black didn't mess that up compared to the bright. In other words, only good for mars, jupe, and saturn. Not enough light sensitivity for the outer planets, and nothing else has good colors anyway. The cheapo cameras didn't do much for say, the nebula in Orion at all -- too dim.

I definitely noticed I got better effective seeing out of the BW camera with a color filter in front - since there was only a narrow band of wavelengths, you only got the one smear, not tons for blue and less for red, all mixed together. Often the best combo was the red plus the IR stop. Since my eyes stink at red, the fact that it was BW coming out of the computer made it nicer than through the eyepiece in that case.
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Re: Big Sky Panorama

Postby Joe Jarski » Thu May 12, 2011 11:38 pm

That's interesting about the filters. I'll have to learn more about how those are made. I had thought about doing a mirror in my chamber if I ever get around to it. The door has a 13-1/4" hole so it can fit something sizable through it and I'm working on converting an old buzz box welder over to a PS that would work for SiO evaporation ~2V and 500A with a big variac to adjust it.

That panorama is cool and the detail is incredible when you zoom up. Like Doug said, just looking through a NVD at the sky is amazing because there are no empty spots.
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Re: Big Sky Panorama

Postby Jerry » Fri May 13, 2011 1:47 am

Yeah, I really got to get back to the vacuum system sometime. Maybe once I finish this darn laser cutter, which I havnt been feeling the motivation on lately.
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