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Uranus System Imaging
Guest_MichaelPoole_*
post Nov 30 2017, 05:03 PM
Post #106





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Thanks for giving me hope. Can a quick colorization of this image of Miranda http://www.planetary.org/multimedia/space-...t-image-of.html image using the low res color data be done through? I'll attempt it myself, I just have very little experience with graphics editing and have only GIMP to use. I just feeling a color picture is more immersive in a "feel like being there" way and I don't wanna have a BW wallpaper and the color data for Miranda seem to be near uniform (basically it's all a very mild pinkish color). I'd be really thankful if someone did it, through I am gonna attempt it myself.
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Guest_MichaelPoole_*
post Nov 30 2017, 06:06 PM
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Here is my very quick and very dirty attempt using GIMP:
http://tinypic.com/r/akuz5c/9 using color from the NASA pic
http://tinypic.com/r/2zio48m/9 using color from the wallpaper pic

To be honest it sucks.
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JohnVV
post Nov 30 2017, 08:43 PM
Post #108


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as an example of what phil posted ( post # 103 ) about needing to remap to add color and the LARGE amount of time needed to do it scientifically correct ( not a very fast job )

see my thread here

http://www.unmannedspaceflight.com/index.php?showtopic=8198

and this was a very fast and very quickly done example that would need about 8 or so more hours for a better job on just that ONE AREA

this dose take a lot of time to do right
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Guest_MichaelPoole_*
post Dec 1 2017, 05:31 PM
Post #109





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QUOTE (JohnVV @ Nov 30 2017, 09:43 PM) *
as an example of what phil posted ( post # 103 ) about needing to remap to add color and the LARGE amount of time needed to do it scientifically correct ( not a very fast job )

see my thread here

http://www.unmannedspaceflight.com/index.php?showtopic=8198

and this was a very fast and very quickly done example that would need about 8 or so more hours for a better job on just that ONE AREA

this dose take a lot of time to do right


I know...could a rough approximation be made quicker?
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JohnVV
post Dec 1 2017, 09:26 PM
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i might have some time on sunday ? maybe

BUT!!!!! there will be NO!!! color band corection from the Orange,green,Blue,violet , and UV images other than a guess ( NO MATH INVOLVED)
nor will i have time ti unwarp the images do to the lens distortion

the reasue marks ann lens distortion lines can be removed easily , so can missing lines of the image

making control nets are VERY time consuming , but some minor warping in the mapping can be done with just 3,4,or5 points and not 100+ points
but that is a very basic realigning of the remaped color filter images

for a very fast done sets for
Ariel , Umbriel , Titania , Oberon , Miranda,
now for the "rocks" in orbit there are spectragraph sets of data for the over color

but even some very fastly done color images of the major moons WILL take time
a few days if not a week or more

and right now i really do not have much free time so 2 to 3 hours at most a night a few nights a week

will take some time
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Guest_MichaelPoole_*
post Dec 1 2017, 11:29 PM
Post #111





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QUOTE (JohnVV @ Dec 1 2017, 10:26 PM) *
i might have some time on sunday ? maybe

BUT!!!!! there will be NO!!! color band corection from the Orange,green,Blue,violet , and UV images other than a guess ( NO MATH INVOLVED)
nor will i have time ti unwarp the images do to the lens distortion

the reasue marks ann lens distortion lines can be removed easily , so can missing lines of the image

making control nets are VERY time consuming , but some minor warping in the mapping can be done with just 3,4,or5 points and not 100+ points
but that is a very basic realigning of the remaped color filter images

for a very fast done sets for
Ariel , Umbriel , Titania , Oberon , Miranda,
now for the "rocks" in orbit there are spectragraph sets of data for the over color

but even some very fastly done color images of the major moons WILL take time
a few days if not a week or more

and right now i really do not have much free time so 2 to 3 hours at most a night a few nights a week

will take some time


Thank you. I really appreciate this. I feel like the moons of Uranus are underappreciated because of the somewhat unphotogenic pictures of them generally published and the great coverage of the Saturnian satellites vs those of Uranus. That creates a false impression of the Uranus's moons as boring despite Miranda's crazy geology, Ariel's likely past ammonia-water solution volcanism, Titania's tectonic features, Umbriel's dark terrain with a single white crater (reminds me of the dark side of Iapetus). The Uranus system should be something different than just a source of scatological jokes to native English speakers (I am not mentioning native English speakers out of prejudice, but because the "Uranus" jokes don't really work in any other language... my native language is Slovak and Uranus is called Urán here, same as the element of Uranium, I thought as a kid that Uranus was radioactive before I read about Voyagers and stuff, but the word for well that body part is completely different in Slovak).

In a way, I acquired a mild obsession about the Uranus system after NH arrived at Pluto. Currently, the moons of Uranus and the planet itself are the least explored rounded bodies in the Solar System apart from Kuiper Belt Objects other than Pluto. In particular Ariel and Miranda fascinate me with their geology.
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jccwrt
post Feb 10 2019, 05:18 AM
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Here's my attempt at processing a composite image from the color sequence and ring mosaic taken on January 23, 1986. I have done some work to bring out some of the cloud present in the longer-wavelength images, primarily by differencing the orange wavelength filter (where the upper level haze is most transparent to Voyager's camera system) with the violet filter (which is dominated by haze scattering). I modified the differenced image a little to produce a synthetic "red" channel. In addition, it was partially used as a luminance channel to help the color variations stand out a little more.

Although the overall appearance is still relatively bland, a south polar and temperate cloud belt are visible. It also looks like the cirrus cloud that is visible in most processings of this image set appears to be correlated to the storm system that Erich Karkoschka found in stacked images back in 2014.

There were numerous stars in the ring mosaic. I suspect that a lot of these are moons, but none matched the ephemerides positions in OPUS' Uranus Viewer so I can't say for sure what's what.


Uranus and Rings - Voyager
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Antdoghalo
post Jun 12 2020, 04:37 AM
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Found this really cool 5K high resolution map of Miranda by Robin Charles Gilbert. While there are other maps of Miranda, I have yet to see any others that really showcase the full resolution of the Voyager images quite like this one.
http://www.robingilbert.com/blog/2017-08-2...las-of-miranda/


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TrappistPlanets
post Apr 29 2021, 12:04 PM
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QUOTE (Antdoghalo @ Jun 12 2020, 04:37 AM) *
Found this really cool 5K high resolution map of Miranda by Robin Charles Gilbert. While there are other maps of Miranda, I have yet to see any others that really showcase the full resolution of the Voyager images quite like this one.
http://www.robingilbert.com/blog/2017-08-2...las-of-miranda/



very nice, wander is there any hidden uranuan back shine on oberon and miranda no one exposed yet?
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JRehling
post Apr 29 2021, 10:28 PM
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When a Uranian pole is pointed more or less at the sun, then the potential uranusshine on a moon would be on the ~1/4 of the surface that can, at that time, see the planet but not the Sun. It's a considerably worse case than with Jupiter or Saturn.

That said, it was a challenge for Voyager to take images of the moons even in sunlight, since the cameras were spec'ed only for Jupiter and Saturn. The light of a half Uranus would be orders of magnitude less than sunlight, so it seems far out of the realm of possibility for those cameras.
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TrappistPlanets
post Apr 30 2021, 12:42 PM
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QUOTE (JRehling @ Apr 29 2021, 10:28 PM) *
When a Uranian pole is pointed more or less at the sun, then the potential uranusshine on a moon would be on the ~1/4 of the surface that can, at that time, see the planet but not the Sun. It's a considerably worse case than with Jupiter or Saturn.

That said, it was a challenge for Voyager to take images of the moons even in sunlight, since the cameras were spec'ed only for Jupiter and Saturn. The light of a half Uranus would be orders of magnitude less than sunlight, so it seems far out of the realm of possibility for those cameras.

so why did we get night shine on titania and ariel, but not miranda and umbriel?
miranda is closer to uranus then ariel and titania, so realistically it should have had stronger uranushine on miranda's night then titania and ariel, therefor making some of its night side features, like craters and cracks a bit clearer then ones on titania and ariel
onless uranus was in the wrong spot at the wrong time so we didn't see any uranusshine on miranda...



wait ted revealed some night shine on miranda, but i think there is more hidden from view like we should have seen more as voyager departed miranda, kinda like with triton when ted pulled out neptune shine on a triton image taken during departer
https://planetary.s3.amazonaws.com/image/mi...thnightside.jpg

you could also possibly pull some uranushine from https://upcimages.wr.usgs.gov/voyager/vg_00...5.thumbnail.jpg

and get some higher res uranushine from https://upcimages.wr.usgs.gov/voyager/vg_00...0.thumbnail.jpg and https://upcimages.wr.usgs.gov/voyager/vg_00...7.thumbnail.jpg


and for umbriel, did ted even tinker with that moon yet? because there is no umbriel night shine in this article
https://www.planetary.org/articles/1362


how did ted pull the neptune shine from triton images, and how did he pull uranusshine from titania, miranda, and ariel?
i want to see if i can try it myself and see if i can pull more uranushine from miranda and possibly oberon (altho i dout it that oberon has any visible uranusshine with what JRehling said)


---edit---
i made a map with miranda's night side with the map antdog found and ted's processed image
Attached Image
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JRehling
post May 2 2021, 05:24 AM
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I definitely committed the sin of posting based on seconds of mental arithmetic rather than something firmer, and Ted's images visibly contradict my guesstimates, so I got a little more serious about it.

First, the moons obviously differ in distance from Uranus, so the light they receive from it vary in this proportion.
If Oberon = 1 unit of luminance from Uranus, the others receive:

Miranda 20.5, Ariel 9.3, Umbriel 4.8, Titania 1.8.

Uranus is huge in each of their skies (22.7° at Miranda!) but seen in a half phase, which I estimate to be 1/4 of the light of a full Uranus, based on hard data from Venus, which is likewise a bland cloudy (and lambertian) ball. Of course, the sunlight at Uranus is 1/360 of that at Earth, but that is relative if we are comparing the sunlit portions of the moons with the uranus-lit.

In a nutshell, the uranus-shine is much brighter than, say, earthshine on the Moon in a given orbital configuration, as a fraction of sunlight at the respective distances from the Sun. In this respect, the half uranus shine on each moon is this ratio of full earthshine on a slender crescent Moon: Miranda 38, Ariel 17.5, Umbriel 9, Titania 3, Oberon 2. In absolute terms, the uranus shine is much dimmer than earthshine on the crescent Moon (divide all of those by 360).

What I fundamentally did not take into account is that the need to slew the spacecraft, a fact I'd known anecdotally, was only necessary for closer images. Full-disc images taken from a distance did not have such a requirement and the exposures were quite long – about 15 seconds. As you can see by snapping an image of the earthshine Moon with your pocket phone camera, getting earthshine in an image with the crescent is not so hard even with a short exposure and 15 seconds at Uranus (for, say, Oberon) is about the same at 0.1 seconds exposure of the Moon.

Note that with the Moon, it is difficult to capture earthshine on a photo of the half Moon or fuller phases because the glare of the sunlit portion destroys the earthshine portion. At Uranus, with those ratios of 2 to 38, that difficulty is overcome.

Now as for why any given image that seems like it might have shown uranusshine but did not, I would want to check on the albedo of that moon, the uniformity of albedo across its surface, and the exposure duration.

I hope this makes amends for my hasty and incorrect estimates before.
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TrappistPlanets
post May 2 2021, 10:35 AM
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QUOTE (JRehling @ May 2 2021, 05:24 AM) *
I definitely committed the sin of posting based on seconds of mental arithmetic rather than something firmer, and Ted's images visibly contradict my guesstimates, so I got a little more serious about it.

First, the moons obviously differ in distance from Uranus, so the light they receive from it vary in this proportion.
If Oberon = 1 unit of luminance from Uranus, the others receive:

Miranda 20.5, Ariel 9.3, Umbriel 4.8, Titania 1.8.

Uranus is huge in each of their skies (22.7° at Miranda!) but seen in a half phase, which I estimate to be 1/4 of the light of a full Uranus, based on hard data from Venus, which is likewise a bland cloudy (and lambertian) ball. Of course, the sunlight at Uranus is 1/360 of that at Earth, but that is relative if we are comparing the sunlit portions of the moons with the uranus-lit.

In a nutshell, the uranus-shine is much brighter than, say, earthshine on the Moon in a given orbital configuration, as a fraction of sunlight at the respective distances from the Sun. In this respect, the half uranus shine on each moon is this ratio of full earthshine on a slender crescent Moon: Miranda 38, Ariel 17.5, Umbriel 9, Titania 3, Oberon 2. In absolute terms, the uranus shine is much dimmer than earthshine on the crescent Moon (divide all of those by 360).

What I fundamentally did not take into account is that the need to slew the spacecraft, a fact I'd known anecdotally, was only necessary for closer images. Full-disc images taken from a distance did not have such a requirement and the exposures were quite long – about 15 seconds. As you can see by snapping an image of the earthshine Moon with your pocket phone camera, getting earthshine in an image with the crescent is not so hard even with a short exposure and 15 seconds at Uranus (for, say, Oberon) is about the same at 0.1 seconds exposure of the Moon.

Note that with the Moon, it is difficult to capture earthshine on a photo of the half Moon or fuller phases because the glare of the sunlit portion destroys the earthshine portion. At Uranus, with those ratios of 2 to 38, that difficulty is overcome.

Now as for why any given image that seems like it might have shown uranusshine but did not, I would want to check on the albedo of that moon, the uniformity of albedo across its surface, and the exposure duration.

I hope this makes amends for my hasty and incorrect estimates before.


so why does miranda has less known uranusshine then ariel
and why is there no known uranusshine on umbriel if its partner titania had some
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Antdoghalo
post May 2 2021, 12:44 PM
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QUOTE (TrappistPlanets @ May 2 2021, 06:35 AM) *
so why does miranda has less known uranusshine then ariel
and why is there no known uranusshine on umbriel if its partner titania had some

The angle Voyager imaged each moon. Miranda is just so close Uranusshine is brighter there even though it was imaged nearly as a full disk. If Miranda was imaged as a crescent like Triton was, it is likely Uranusshine would have been prominent. Voyager 2 was unable to do so until it was further out because of the multitude of targets Voyager encountered at Uranus and the speed and increased exposure time needed, not to mention, the Uranian moons were off the ecliptic (Uranus and its tilt problems) and we still needed to get to Neptune, while not frying the lens from sunlight.


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Phil Stooke
post May 2 2021, 07:27 PM
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Since this is the 20th anniversary of the discovery of planetshine on the Uranian satellites (reported at LPSC in March 2001, abstract attached here), it's good to get back to it again.

This link:
https://www.planetary.org/articles/1362
discusses the situation in more detail with some of Ted Stryk's processed images.

As Voyager 2 approached the Uranian system the moons were spread out around it and viewed at closest approach from different directions. If you get lucky the part of the moon lit by planetshine is going to be visible at closest approach, and that was the case for Ariel. For the others, either the part illuminated by Uranus was facing the other way or it was only seen as a very thin crescent and at lower resolution. Remember that the idea of viewing the 'night' side in reflected light had not been considered by the Voyager science team (or maybe considered but rejected), so imaging was not undertaken with a view to capturing these scenes and anything we got was serendipitous.

Cassini took full advantage of this discovery and we got spectacular results that significantly increased coverage of many moons.

Phil
Attached File  stooke_lpsc_32_satellites_1074.pdf ( 130.24K ) Number of downloads: 254



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... because the Solar System ain't gonna map itself.

Also to be found posting similar content on https://mastodon.social/@PhilStooke
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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