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Uranus System Imaging
machi
post Dec 14 2009, 10:18 AM
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I finished my first good image of Uranus.
Planet is colorized from three filtered images (orange, green, blue).
Slightly brownish color of rings is entirely artificial.
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Bjorn Jonsson
post Sep 13 2014, 08:57 PM
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Shortly after finishing the flyby anniversary mosaic of Neptune I started thinking about Uranus, got an interesting idea, started processing the Voyager 2 Uranus images and came up with this (two versions of the same image):

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I think these may be the most detailed Voyager 2 global images of Uranus I have ever seen (but they are far inferior to recent groundbased images).

The processing idea came from the description of the processing of these images of Uranus:

http://www.planetary.org/blogs/emily-lakda...eck-photos.html

In short, I used 6 orange and 6 green filtered images that I reprojected to simple cylindrical projection, removing (or at least greatly reducing) the effects of global illumination on the fly. This was sufficient to correct for Uranus' rotation but since the images were obtained over a period of ~5 hours this was not sufficient - it's necessary to correct for Uranus' fast east/west zonal winds as well. To do this I found a profile (and I think it's a very recent and up to date one) showing Uranus' zonal wind speed as a function of latitude. I used this to correct the individual cylindrical maps by shifting each image row in the east-west direction. I then stacked the 12 maps, rendered an image and then greatly increased the contrast and visibility of various features. In the left image I first enhanced the contrast and then sharpened the image with an unsharp mask. In the right one I first enhanced the contrast, then suppressed large scale brightness variations with a high pass filter and then further increased the contrast.

The source images were obtained on January 17, 1986 between 14:19:10 and 19:35:10. At this time Voyager 2 was ~9 million km from Uranus.

This is experimental work in progress and it is probably possible to get better results. A day earlier, a longer sequence of images was obtained but it took a longer time; I strongly suspect that there is a limit to how long the time can be if you want good stacking results but I don't know what this limit is. One interesting processing artifact that may occur if the zonal wind profile I'm using is inaccurate is that bright or dark features get too elongated in the east/west direction but I don't think this is a significant issue here. Interestingly, even if this happen the feature's longitudinal position can be accurately estimated as the average of the west and east edges of the feature, as pointed out in a very interesting article by Sromovsky et al. in Icarus 203 (1): 265–286 (2009). EDIT: It's actually in Fry et al., Astronomical Journal vol. 143, no. 6, June 2012 where this is pointed out (the Sromovsky et al. article is very interesting too though).

There is considerable noise in the above images but it should be fairly obvious which features are real and which ones are noise and/or image processing artifacts. All of the obvious bright spots are definitely real and all of the narrow bright/dark east-west cloud belts (there are several of these) should be real as well. The dark, "partial cloud belts" near the bright spots are real as well. Another faint "partial belt" to the right of the dark polar cap may be real but I'm not sure. Some of these features are completely new to me.

With the benefit of hindsight, it is apparent that the best way for Voyager 2 to image Uranus might have been to obtain a few big sequences of orange-only images (orange images show the biggest amount of detail) in as short a time interval as possible, maybe using the tape recorder to speed things up due to the low bit rate possible from Uranus. This would have made the stacking results better. But of course there was absolutely no way to know this back in 1986.

I think the images above might hint at what additional details Voyager 2 could have seen had it been able to carry a Galileo/Cassini-style imaging system with near infrared filters. And they may hint at what a future spacecraft might see if it arrives when the illumination geometry is comparable to what it was in 1986.

Uranus' is *not* an uninteresting planet, it's simply more difficult to observe than the other giant planets due to low contrast and hazes. In my opinion it's at least as interesting as e.g. Neptune - and significantly different from it.
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- machi   Uranus System Imaging   Dec 14 2009, 10:18 AM
- - Hungry4info   That's pretty neat, ^.^, though the rings look...   Dec 14 2009, 01:44 PM
- - machi   Yes, rings look bright, because their brightness i...   Dec 15 2009, 05:08 PM
- - machi   Probably highest resolution image of Uranus with s...   Jan 7 2010, 06:14 PM
|- - tedstryk   Great work! I have always focused on the moon...   Jan 8 2010, 06:41 PM
- - antipode   Hey thats very nice! Has this dataset been ign...   Jan 8 2010, 09:53 AM
- - machi   Possibly. But I think, that lots of information is...   Jan 8 2010, 05:23 PM
- - antipode   Ever since the original data was released, it alwa...   Jan 9 2010, 09:27 PM
- - elakdawalla   If you haven't seen it, you should check out B...   Jan 9 2010, 09:59 PM
|- - Bjorn Jonsson   QUOTE (elakdawalla @ Jan 9 2010, 09:59 PM...   Jan 9 2010, 10:28 PM
- - machi   I have seen Bjorn Jonnsson's image of Uranus a...   Jan 9 2010, 10:34 PM
|- - Bjorn Jonsson   It's actually quite interesting to attempt to ...   Jan 10 2010, 02:47 AM
||- - stevesliva   QUOTE (Bjorn Jonsson @ Jan 9 2010, 10:47 ...   Jan 10 2010, 05:20 AM
||- - Stefan   QUOTE (Bjorn Jonsson @ Jan 10 2010, 03:47...   Jan 10 2010, 02:35 PM
|- - Hungry4info   QUOTE (machi @ Jan 9 2010, 04:34 PM) They...   Jan 10 2010, 03:14 AM
- - machi   I was wrong! Is one image with slightly higher...   Jan 11 2010, 01:40 PM
- - machi   Best image of Uranus south pole. Circular feature ...   Jan 12 2010, 11:05 AM
- - stevesliva   The slightly lighter core inside the darker second...   Jan 12 2010, 04:51 PM
- - machi   Effectively highest resolution view from any of Vo...   Jan 17 2010, 10:50 AM
- - Decepticon   Wow! Love your work.   Jan 17 2010, 01:08 PM
- - machi   Thanks Decepticon! And new image from Uranu...   Feb 16 2010, 03:08 PM
- - machi   Moon Ariel resampled at 1 km/pix (real resolution ...   Aug 16 2010, 09:24 AM
|- - Stefan   Stunning!   Aug 16 2010, 10:51 AM
|- - ugordan   Nice work, keep it coming!   Aug 16 2010, 11:33 AM
- - antipode   WOW! That's the best look at that moon I...   Aug 16 2010, 12:15 PM
- - machi   Stefan and Ugordan: Thanks! Antipode: Actuall...   Aug 16 2010, 12:46 PM
|- - tedstryk   Great work! That is the mosaic I based my fir...   Aug 17 2010, 12:55 AM
|- - DrShank   QUOTE (tedstryk @ Aug 16 2010, 07:55 PM) ...   Aug 17 2010, 01:01 PM
- - machi   QUOTE (tedstryk @ Aug 17 2010, 02:55 AM) ...   Aug 18 2010, 07:28 AM
- - machi   Three images of Titania. All resampled from origin...   Aug 19 2010, 12:08 AM
|- - tedstryk   Very nice work.   Aug 19 2010, 01:07 AM
|- - ugordan   QUOTE (machi @ Aug 19 2010, 02:08 AM) Thr...   Aug 19 2010, 07:32 AM
- - antipode   Ditto. Im enjoying this thread, and enjoying the ...   Aug 19 2010, 02:58 AM
- - machi   Ted: Thanks! Antipode: I'm always enjoyin...   Aug 19 2010, 10:34 AM
|- - tedstryk   I have also noticed the color shift.   Aug 19 2010, 05:26 PM
|- - ugordan   It looks like a calibration artifact at first, but...   Aug 19 2010, 05:49 PM
- - Stu   You see? THIS is why I love UMSF so much... You Im...   Aug 19 2010, 05:58 PM
- - machi   Ugordan, Tedstryk: In case of color shift near the...   Aug 19 2010, 07:32 PM
|- - ugordan   Here's a color version of Titania using calibr...   Aug 22 2010, 04:44 PM
- - sariondil   Machi´s version of the Oberon data set can be used...   Nov 10 2010, 02:39 PM
- - machi   Anaglyph of Titania. It's based on synthetic f...   Apr 13 2011, 04:01 PM
|- - algorimancer   QUOTE (machi @ Apr 13 2011, 10:01 AM) Ana...   Apr 13 2011, 04:27 PM
- - machi   Cross-eye stereo image of Titania. Synthetic image...   Apr 14 2011, 08:56 PM
- - nprev   Daniel, you're a wizard. These are AMAZING.   Apr 15 2011, 01:01 AM
- - Bjorn Jonsson   Agreed, this is amazing. Interestingly the anaglyp...   Apr 16 2011, 02:24 AM
- - nprev   I noticed that the (bear with me on the terminolog...   Apr 16 2011, 03:06 AM
- - machi   Thanks! I see many topographic details, but o...   Apr 18 2011, 12:48 PM
- - ilbasso   Wow! The anaglyph version looks almost like a ...   Apr 18 2011, 06:08 PM
- - Paolo   some new, cool infrared images of Uranus and Neptu...   Sep 27 2011, 05:29 AM
- - stevesliva   One thing that got mentioned on twitter but not th...   Sep 27 2011, 06:38 AM
- - JohnVV   For anyone interested .I put together an artistic ...   Sep 27 2011, 06:53 PM
- - MarcF   I just found the following information: Professio...   Nov 25 2011, 05:25 PM
- - MarcF   Dear all, I just bought the book "Uranus...   Jan 27 2012, 12:45 PM
|- - jasedm   QUOTE (MarcF @ Jan 27 2012, 12:45 PM) Wil...   Jan 27 2012, 05:57 PM
- - Phil Stooke   Check out this website: http://planetarynames.wr....   Jan 27 2012, 02:55 PM
- - MarcF   Thanks Phil, Maybe I will try to suggest some ...   Jan 27 2012, 04:12 PM
- - scalbers   Greetings. Here are the present versions of my Ura...   Feb 19 2012, 05:25 PM
- - scalbers   And here's Umbriel assuming a 265 degree cente...   Feb 19 2012, 05:36 PM
- - scalbers   Finally - here's Oberon: (Updated March 3, ...   Feb 19 2012, 05:37 PM
- - antipode   Little surprised that no one has commented on this...   Apr 16 2012, 05:52 AM
- - Phil Stooke   I only just noticed Steve's question about Pix...   Apr 16 2012, 11:44 AM
- - morganism   Keck observations bring weather of Uranus into sha...   Oct 17 2012, 11:49 PM
|- - Ken90000   Wow. The resolution is incredible. It will be in...   Oct 18 2012, 02:41 AM
- - Phil Stooke   Yes, they really are amazing. I would like to see...   Oct 18 2012, 03:32 AM
- - MarcF   Wow, I cannot believe it ! Uranus as we never ...   Oct 18 2012, 08:18 AM
- - JohnVV   time to remap the above keck images and incorporat...   Oct 18 2012, 09:00 AM
- - Bjorn Jonsson   WOW!!! To me these may be the planetar...   Oct 18 2012, 03:05 PM
- - tasp   I want a Uranus orbiter or flyby mission in my lif...   Oct 18 2012, 04:15 PM
- - machi   Amazing images and amazing technical story. I reme...   Oct 18 2012, 05:35 PM
- - Phil Stooke   Just fooling around with images - and a big thanky...   Oct 19 2012, 01:35 AM
- - elakdawalla   Tonight was the poster session where Larry Sromovs...   Oct 19 2012, 02:44 AM
- - belleraphon1   Incredible.... can hardly believe these are from g...   Oct 19 2012, 07:44 PM
- - MarcF   Finally, "real" Uranus looks quite like ...   Oct 20 2012, 10:52 AM
- - antipode   Impressive post-equinox atmospheric action on the ...   Aug 8 2014, 07:44 AM
- - Bjorn Jonsson   Shortly after finishing the flyby anniversary mosa...   Sep 13 2014, 08:57 PM
- - scalbers   Nice view Bjorn - with a polar pentagon (or maybe ...   Sep 13 2014, 09:28 PM
- - Bjorn Jonsson   I don't know if the polar pentagon/hexagon is ...   Sep 14 2014, 12:11 AM
- - Bjorn Jonsson   Here are two versions of an image from a stack of ...   Sep 15 2014, 11:07 PM
- - MarcF   Wow really nice Bjorn. The latest Keck Observatory...   Sep 30 2014, 09:30 PM
- - Bjorn Jonsson   Uranus once looked dull but it really isn't - ...   Nov 8 2014, 07:35 PM
|- - Stefan   Voyager image processing magic by Erich Karkoschka...   Nov 15 2014, 01:02 PM
- - MarcF   Wow, just great. My favorite planet looks better a...   Nov 16 2014, 03:37 PM
- - antipode   Record-breaking Storm Activity on Uranus in 2014 ...   Jan 8 2015, 04:25 AM
- - Explorer1   A key quote: QUOTE But even with such data, some...   Jan 8 2015, 04:40 AM
- - TheAnt   Could it be that Uranus have a more quiet period w...   Jan 29 2015, 12:39 PM
- - nprev   I'd always assumed that was exactly the workin...   Jan 29 2015, 06:13 PM
|- - TheAnt   QUOTE (nprev @ Jan 29 2015, 07:13 PM) I...   Jan 31 2015, 01:59 AM
- - antipode   Wow. Keck AO does it again. http://www.sciencedir...   Jun 5 2015, 10:23 AM
|- - rboerner   QUOTE (antipode @ Jun 5 2015, 02:23 AM) L...   Jun 5 2015, 08:03 PM
- - Ian R   RE: Uranus System Imaging   Jun 6 2015, 03:02 AM
- - Ian R   Look at the equatorial band of scalloped clouds...   Jun 6 2015, 03:09 AM
- - antipode   More astonishing AO imaging from Keck II and Gemin...   Dec 17 2015, 06:14 AM
- - MarcF   Voyager Mission Celebrates 30 Years Since Uranus: ...   Jan 23 2016, 09:57 PM
- - Bjorn Jonsson   Today is the Voyager 2 Uranus 30 year flyby annive...   Jan 24 2016, 03:10 PM
|- - JRehling   A world that these images remind me of, visually, ...   Jan 25 2016, 07:26 PM
- - nprev   ..."not exactly detailed", but stunning ...   Jan 24 2016, 03:51 PM
- - Bjorn Jonsson   Interesting comparison to Mercury. The albedo vari...   Jan 26 2016, 12:18 AM
|- - tedstryk   Sorry, I'm just finding this now. Excellent w...   Jan 26 2016, 02:23 PM
- - Astroboy   A gif of the 1/23/1986 Titania phase angle coverag...   Jun 11 2016, 04:07 AM
- - Astroboy   Not as clean looking as the first image in this th...   Aug 28 2016, 07:51 PM
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