Adaptive Optics, Tracking the SOTA for ground-based observation |
Adaptive Optics, Tracking the SOTA for ground-based observation |
Nov 16 2016, 06:23 PM
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#1
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Here, as mentioned in the Neptune thread, is a link to an article about the PALM-3000 system working with the 5m Hale Telescope. The attached photo of Ganymede is one of the best ground-based images I've ever seen, and easily blows away HST resolution.
http://inspirehep.net/record/1252803/plots
Attached image(s)
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Nov 16 2016, 08:35 PM
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#2
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IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Wow!!!!
Somehow the fact that groundbased images of the Galileans have become as good as the image above had escaped my attention. Keeping in mind what the best images so far of e.g. Uranus look like (they show lots of belts and spots), the next several years are going to be interesting for everyone interested in the outer solar system. |
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Nov 17 2016, 02:14 AM
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#3
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Solar System Cartographer Group: Members Posts: 10226 Joined: 5-April 05 From: Canada Member No.: 227 |
Wow indeed. Amazing. OK, now I want to see... the list is never-ending!
This is the same side of Ganymede seen by Galileo: (lousy pic pulled off the web quickly, as I am otherwise occupied right now) Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Nov 17 2016, 07:57 AM
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#4
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Senior Member Group: Members Posts: 1276 Joined: 25-November 04 Member No.: 114 |
The features don't seem to line up?
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Nov 17 2016, 08:25 AM
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#5
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Member Group: Members Posts: 593 Joined: 20-April 05 Member No.: 279 |
Rotate Phil's 90° clockwise.
Andy |
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Nov 17 2016, 03:01 PM
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#6
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
It certainly is impressive. Not quite Voyager level, and we don't get to choose the perspective, but the increased resolution of ground-based observations is something of an escape valve on the pressure to launch certain outer solar system missions, and is bound to improve with time.
Roughly speaking, resolution is a linear function of aperture, and that 5 meter telescope is delivering resolutions about 40 times better than a telescope with about a 40th the aperture. This would not have been the case in the past, with "seeing" limiting the resolution of a massive telescope. But that's now changed. When we have 30-to-40 meter telescopes served by the next decade's technologies, we may get pictures of, say, the Uranian satellites that exceed Voyager coverage, and imaging other latitudes as the seasons to change will just be a matter of waiting. |
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Nov 17 2016, 03:18 PM
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#7
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Solar System Cartographer Group: Members Posts: 10226 Joined: 5-April 05 From: Canada Member No.: 227 |
"Rotate Phil's 90° clockwise."
No, rotate the other one! Mine has north at the top. Call me old-fashioned but that's the way I like it. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Nov 17 2016, 05:56 PM
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#8
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Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
Thanks for posting. That is crazy impressive resolution
What ever happened to the promise of optical interferometry, with multiple telescopes separated by large distances to emulate the performance of a larger scope? We had Keck II, which did some impressive work, but that was more of a pilot project for the larger plans. |
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Nov 17 2016, 06:42 PM
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#9
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
What ever happened to the promise of optical interferometry, with multiple telescopes separated by large distances to emulate the performance of a larger scope? We had Keck II, which did some impressive work, but that was more of a pilot project for the larger plans. Definitely the preeminent telescope of the future is the E-ELT, which will have a 39-meter composite mirror. You could think of that as multiple telescopes separated by a distance, but with extra telescopes filling in all the space between them! If that can deliver an 8x improvement on the resolution in the Ganymede photo that I posted, as it should, it'll as big of an advance over existing telescopes than the HST was over what came before it. I'm not sure why the architecture that you mention has not been advanced, but there was a great article in SiAm last year… https://www.scientificamerican.com/article/...from-yesterday/ …about the very acrimonious and political battle to develop the world's next biggest telescopes that was a bitter fight over resources and ended up not with one big winner, nor two, but three roughly equal rivals. As the article mentions, a unified community would probably have given the world a single massive telescope many years earlier. That's the downside. The upside is that we'll probably have two of them a decade from now, and that doubles the number of observations. (The third, TMT, is in limbo due to even different political reasons, but we may have three massive telescopes 15 or 20 years from now???) Given the intense struggle and animosity, it's likely that many worthwhile projects have been stalled by the fierce competition for resources. The world's biggest radio telescope has also been built, in China. There's no doubt we're on the cusp of a new golden age of telescopes, and many breakthroughs are inevitably to follow. Personally, I'm most excited about the visual observation of exoplanets within 50-100 light years, but it's also sure to mean breakthrough observations of objects as close as the asteroid belt and as far as the cosmological scale. |
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Nov 17 2016, 07:54 PM
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#10
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Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
I see that there is the ESO's VLTI, which is a large telescope system which uses interferometry:
https://www.eso.org/sci/facilities/paranal/...copes/vlti.html However, I can only find extra-solar results for the VLTI. They did do some neat adaptive optics imaging of Jupiter though, but they don't seem to have used interferometry to do it: https://www.eso.org/public/images/eso0833a/ |
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Nov 17 2016, 08:15 PM
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#11
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Solar System Cartographer Group: Members Posts: 10226 Joined: 5-April 05 From: Canada Member No.: 227 |
I don't know a lot about this, but my impression is that interferometry is really good at separating very close point sources (close binaries, whether stars or asteroids, don't know if it's so good with s star plus planet pair because of the huge difference in brightness) but has not been so successful with imaging of extended objects. Adaptive optics seems to be much better at producing images.
Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Nov 17 2016, 08:19 PM
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#12
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Senior Member Group: Members Posts: 1276 Joined: 25-November 04 Member No.: 114 |
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Nov 18 2016, 03:21 PM
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#13
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Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
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Nov 18 2016, 08:55 PM
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#14
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
I see that there is the ESO's VLTI, which is a large telescope system which uses interferometry: https://www.eso.org/sci/facilities/paranal/...copes/vlti.html However, I can only find extra-solar results for the VLTI. They did do some neat adaptive optics imaging of Jupiter though, but they don't seem to have used interferometry to do it: https://www.eso.org/public/images/eso0833a/ According to Wikipedia, VLTI works only for very bright objects, i.e. for nearby stars: QUOTE Because of the many mirrors involved in the optical train, about 95 percent of the light is lost before reaching the instruments at a wavelength of 1 µm, 90 percent at 2 µm and 75 percent at 10 µm.[40] This refers to reflection off 32 surfaces including the Coudé train, the star separator, the main delay line, beam compressor and feeding optics. Additionally, the interferometric technique is such that it is very efficient only for objects that are small enough that all their light is concentrated. For instance, an object with a relatively low surface brightness such as the moon cannot be observed, because its light is too diluted. They reference the document "Puech, F.; Gitton, P. (2006). "Interface Control Document between VLTI and its instruments". VLT-ICD-ESO-15000-1826", which I didn't find online, possibly exists only as print version. Wikipedia also says: QUOTE When fringe tracking is introduced, the limiting magnitude of the VLTI is expected to improve by a factor of almost 1000, reaching a magnitude of about 14. |
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Nov 18 2016, 10:10 PM
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#15
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Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
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