Juno perijove 5, March 27, 2017 Options

[Bjorn Jonsson]

Juno's perijove 5 is coming up less than two weeks from now - it's on March 27, 2017.

The target selection voting has started and is open until almost four days from now: https://www.missionjuno.swri.edu/junocam/voting?current

A large part of the data volume will be reserved for polar time lapse sequences though.

John Rogers has written a helpful summary of the upcoming perijove 5: https://www.britastro.org/node/9377

[PhilipTerryGraha...]

An insignia for perijove 5 that I made for the subreddit.

[JRehling]

Nice, Philip! (The board should have "Like" button…)

[belleraphon1]

Very cool Philip!

My desktop for March 27th

You plan to make one for each perijove?

Craig

[PhilipTerryGraha...]

Ehyup! I've got a few ideas for graphics each time the spacecraft comes 'round.

[PhilipTerryGraha...]

The word from NASA: all instruments will be on, and the spacecraft will be making a closest approach of around 4,400 kilometers, with a top speed of 57.8 kilometers per second, relative to Jupiter.

[PhilipTerryGraha...]

Here's what Juno's signal looked like at closest approach on Perijove 5, capped from DSN Now at 09:30 UTC (08:57 UTC + 37 minutes, the current light travel distance from Earth to Jupiter). This has occurred only 7 minutes ago, as of me posting this.

[PhilipTerryGraha...]

Madrid downlinking data from the spacecraft at the moment, at a rate of 40 kilobits per second according to DSN Now. Fun fact - this is 325 times slower than the average download speed of my ADSL2 modem. I feel like I've been taking my Australian copper wire internet for granted.

[Bjorn Jonsson]

On the other hand this is almost 1000 times faster than the typical Galileo downlink speed from Jupiter was.

[PhilipTerryGraha...]

Imagine how different the Galileo mission would've been if that High-gain antenna had worked.

[Explorer1]

Things would be quite different, though I always prefer to look at the bright side of the Jupiter data loss. I bet there would be more missions afterward with antennas that deployed mechanically long after launch, and some other mission would have had the issue. We know better now.

[Bjorn Jonsson]

That was fast - the PJ5 images are now available at the Juno website.

[PhilipTerryGraha...]

The image of Trevmation's Dark Spot was reportedly taken at a distance of only 3,421.8 km, according to its metadata. Can this be true? Because if so, that's a thousand kilometers less than expected, and most certainly the closest approach of the mission so far.

[Gerald]

Usually the metadata are pretty accurate. However, I'm in an early phase of processing, so can't yet verify by the images.

... Here an enhanced draft of PJ05, #109, rendered from the raw, yet without proper calibration nor trajectory or shape model, therefore the color channel poorly aligned. However, it's very facinating already, including dark boundaries along clouds, which look like shadows.

[mcaplinger]

The image of Trevmation's Dark Spot was reportedly taken at a distance of only 3,421.8 km, according to its metadata. Can this be true? Because if so, that's a thousand kilometers less than expected...

Expected by who?

Obviously the metadata was computed with a predicted spacecraft position and that may change a little once we have the reconstruction, but I'm fairy confident that the calculation is right. Keep in mind that because of Jupiter's oblateness, the geometry to figure out the altitude is a little more complex than simply taking the distance to the center of Jupiter and subtracting the radius of Jupiter, which is what a simple calculation might do.

Here's the code that computes the metadata if you're interested (in Python, using NAIF/pyspice):

CODE

te = spkezr("juno", t, "iau_"+target, "LT+S", target)[0][0:3]
radii = bodvrd(target, "RADII", 3)[1]
lon, lat, alt = recpgr(target, te, radii[0], (radii[0]-radii[2])/radii[0])

[Gerald]

Polar projection of PJ-05 image #111, and detail, enhanced in different ways:


(NASA / JPL / SwRI / MSSS / Gerald Eichstädt)

Thanks to the Juno-Ops team for your outstanding work! Despite the tight memory constraints of PJ05, we've got a sequence of images of high quality, as far as I can already say about the images I've preliminarily processed thus far.

[PhilipTerryGraha...]

Looks like Jupiter is happy to see Juno again

[Roman Tkachenko]

Jupiter, Io and Europa.

[mcaplinger]

Lightly-processed quicklook version of image pj5-110. I'm sure others will do a better job.

[Roman Tkachenko]

#110

[Decepticon]

Roman that is beautiful!

[Gerald]

Is it possible to discern any rotation in these large storms within the five and a half minutes between images #109 and #110?
My best candidate is the large white (anticyclonic) oval A6:

(crop of cylindrical planetocentric projection with 60 pixels / deg, de-Lambertianed, and further enhanced, north to the right)

[Decepticon]

Can Juno image lightning on the dark side?

[Gerald]

Yes, but there are also energetic particle events and camera artifacts. So, we need to look twice, before making conclusions.

[Gerald]

Spacecraft changing spin axis (and observation mode) during PJ05 approach:

Colors approximately radiometric, then square-root encoded. South is up. Note the Great Red Spot, and a moon shadow.

For this sequence, I've calibrated my simplfied geometrical camera model for each image separately during an overnight calibration run.
With this kind of sequences covering spacecraft attitude changes, I'm hoping and expecting to be able to further narrow down the actual geometrical camera properties, among other approaches.

[Gerald]

For completeness, here the statistics resulting from the calibration run:

There are peaks and discontinuities near the change of the s/c spin axis.

But at least the camera's optical axis shouldn't change during these maneuvers, with the x-position near 812. The inconsistencies indicate residual flaws in the model, and help to uncover them.

[Roman Tkachenko]

#109

[scalbers]

That has some super detail in it, including what look like convective cloud elements. Do we know what the pixel resolution is? Considering the context, these convective clouds on the right are in a zone, with overall low altitude clouds, so that we see more into a water rich level. The redder clouds on the left are in a higher belt. It seems the bluer nature of the zone would be consistent with looking through some overlying clear air with attendant Rayleigh scattering.

[mcaplinger]

Do we know what the pixel resolution is?

Altitude from the metadata is 12744 km, so resolution is 673e-6*12744 = 8.6 km/pix at nadir.

[scalbers]

Thanks - we can see the sizes of the convective clouds are similar to thunderstorms on Earth.

[Bjorn Jonsson]

For completeness, here the statistics resulting from the calibration run:

Have you checked how accurate the interframe delay in the metadata is? For the PJ5 images it is 0.371 but I'm starting to suspect that I might get slightly better results by adjusting it slightly. I haven't tried it yet though but I'm pretty sure any adjustment (if needed) is less than 0.001.

Is it possible to discern any rotation in these large storms within the five and a half minutes between images #109 and #110?
My best candidate is the large white (anticyclonic) oval A6:

Quick back of the envelope calculations seem to suggest this *might* be possible. The elapsed time between the images is ~330 seconds. Assuming a wind speed of ~60 m/s near the A6 spot's periphery (a very crude but probably not bad assumption made by scaling down the speed in the bigger white oval BC in the Voyager era by a factor of ~2 since A6 is smaller) results in a ~20 km movement. This corresponds to roughly 2-3 pixels in the higher-res image which is noticeable if the images are well aligned.

That has some super detail in it, including what look like convective cloud elements. Do we know what the pixel resolution is? Considering the context, these convective clouds on the right are in a zone, with overall low altitude clouds, so that we see more into a water rich level. The redder clouds on the left are in a higher belt. It seems the bluer nature of the zone would be consistent with looking through some overlying clear air with attendant Rayleigh scattering.

Hmmm... but I have always been under the impression that the whitish zones are higher in the atmosphere than the darker and more reddish/brownish belts and that they are probably ammonia cirrus (the water clouds are much lower in the atmosphere and look darker and more fuzzy). But the possible convective clouds in Roman's image are very interesting. An interesting fact is that these small, whitish clouds are very common and not just in Roman's image. They occur both as isolated features, e.g. at ~(435,740) and in 'clusters', e.g. at ~(980,105) in Roman's image above. And there's a lot of them in the whitish zone. Some of them look like cumulus to me. These clouds seem to occur at various locations although some areas are more likely to have them than others.

There are also small/narrow 'elongated', whitish clouds at various locations, typically above darker clouds. I suspect their altitude is similar to the convective/cumulus clouds. Here is an example, an enhanced crop from an image (PJ5 image 110) I'm working on:

[mcaplinger]

Have you checked how accurate the interframe delay in the metadata is? For the PJ5 images it is 0.371...

The metadata value is 1 millisecond too small (there was an off-by-one misunderstanding about how the hardware interpreted the commanded interframe value.) Otherwise it's under the control of a fairly stable crystal oscillator but there could be some drift on order of 10-20 PPM over temperature.

The spacecraft spin rate is usually not precisely 2.000 RPM so that's probably a bigger unknown.

[scalbers]

Hmmm... but I have always been under the impression that the whitish zones are higher in the atmosphere than the darker and more reddish/brownish belts and that they are probably ammonia cirrus (the water clouds are much lower in the atmosphere and look darker and more fuzzy). But the possible convective clouds in Roman's image are very interesting. An interesting fact is that these small, whitish clouds are very common and not just in Roman's image. They occur both as isolated features, e.g. at ~(435,740) and in 'clusters', e.g. at ~(980,105) in Roman's image above. And there's a lot of them in the whitish zone. Some of them look like cumulus to me. These clouds seem to occur at various locations although some areas are more likely to have them than others.

Thanks Bjorn for the correction/clarification. I was somewhat influenced by the appearance of the image where it seemed like some of the belt clouds were running on top of the zone clouds at the border - perhaps an illusion. I will suggest that the zones would have a mix of elevation as I believe IR hot-spots (bluish in visible) tend to occur in the zones and we may be seeing some of these on a small scale in this closeup. These hot-spots are areas with very few (or very low) clouds. It would be interesting to look at closeup IR data or something like that to tell the relative altitude of the convective cloud bottoms and tops relative to the more stratiform white (ammonia) clouds. Maybe stereo images can help on this as well.

Within the belts, are the white spots higher or lower than the surrounding reddish clouds?

[Bjorn Jonsson]

Maybe stereo images can help on this as well.

I think it might be possible to use images 109 and 110 as a stereo pair. I haven't tried it yet but probably will.

[scalbers]

This is a good learning experience for me. If we look at this hi-res IR/visible pair we can see most of the hot spots are in the brown belts as you suggest. However some bluish areas continue into the zones with "suppressed" IR warmings. This suggests to me the bluish areas in the zones are areas fairly cold in IR with thin high ammonia haze, while also allowing us a partially transparent view with scattered visible light into much lower altitudes.

http://www.dailymail.co.uk/sciencetech/art...approaches.html (scroll down page to see image pair and look just right of center in the images)

Areas that are dark within the belts look to be the hottest of all, perhaps no clouds are present at all in these locations.

Will be interesting if we can see some simultaneous images of the VLT IR data and Juno. The link is showing images from the ESO VLT and ground-based visible light images as a dry run for the Juno observing campaign.

A similar situation occurs with satellite images of Earth with thin cirrus clouds. The IR signature looks cold while in the visible it can be relatively dark (blue in color) with the ground still evident.

[jccwrt]

Hmmm... but I have always been under the impression that the whitish zones are higher in the atmosphere than the darker and more reddish/brownish belts and that they are probably ammonia cirrus (the water clouds are much lower in the atmosphere and look darker and more fuzzy). But the possible convective clouds in Roman's image are very interesting. An interesting fact is that these small, whitish clouds are very common and not just in Roman's image. They occur both as isolated features, e.g. at ~(435,740) and in 'clusters', e.g. at ~(980,105) in Roman's image above. And there's a lot of them in the whitish zone. Some of them look like cumulus to me. These clouds seem to occur at various locations although some areas are more likely to have them than others.

It's possible that the white spots are a form of pileus in the ammonia cirrus deck or perhaps even overshooting tops of water vapor cumulus. Given some of the Voyager images you found in a similar region last year, I'm inclined to say it's the latter, but I don't know enough about Jovian meteorology to say if a water vapor-driven updraft is capable of rising that high through the cloud deck without collapsing.

This is a good learning experience for me. If we look at this hi-res IR/visible pair we can see most of the hot spots are in the brown belts as you suggest. However some bluish areas continue into the zones with "suppressed" IR warmings. This suggests to me the bluish areas in the zones are areas fairly cold in IR with thin high ammonia haze, while also allowing us a partially transparent view with visible light into much lower altitudes.

The equatorward side of the equatorial belts is marked by a vertical jet stream oscillation. You get an IR hotspots where the jet stream is descending and warming the air through adiabatic heating. That clears out the upper cloud decks to give us an unobstructed view deep into Jupiter (probably down to the water cloud layer), which correspond with the dark blue areas in the VIS along the edge of the belt. The ascending portion oscillation generates a long-lived convective updraft that encourages the formation of ammonia cirrus muddied with some of the ammonium sulfate cloud layer that's been carried upwards. Most of that cirrus drifts equatorwards, but some of it gets entrained within the belt circulation patterns and is forming an IR-blocking layer that shows up against the bright IR radiation emitted from the belts. The belts are also a region of generally descending air, so you might also be getting variable IR bright spots where the ammonium sulfate clouds are being eroded more deeply by adiabatic heating.

[scalbers]

We can see these variable hot-spots in the belts as I'm here reproducing one of the images from the link in post #35. The IR blocking areas in the belts appear to be where white clouds are mixing with the red ones. However the white clouds in the belts appear different in nature/structure than the white clouds in the zones (in #109), so it's unclear to me whether entrainment from the zones is really going on.



The convective clouds in #109 are mostly in a zone, so I wonder if the visible cumuliform cloud is all an overshooting top, or if we can see (through the cirrus) deeper to the source region of the water vapor. It also seems like the rising motion in the zones would be dynamically forced on the large scale with the convection happening more on the small scales. I would continue to entertain the notion that in the zones we're seeing a combination of thin white high ammonia haze, with more structured denser white clouds at a lower altitude. This possibly explains why we see structure in the visible and not so much in the IR. The convection could be happening between these two levels. Some of the darker areas in the zones (and belts) would be where we are seeing even deeper.

This link is actually suggesting that the zones have large scale descent. Though it's interesting that they say most convective elements are in the belts. Maybe that's true of some larger storms that could be seen in the Cassini flyby in 2000, or the embedded convective elements in the whiter clouds within the belts as in Bjorn's image in post #31. Perhaps looking at Juno's images now is giving some fresh perspectives on all this. Possibly larger convective storms tend to be in the belts and smaller ones in the zones.

On another note I can see rotation in Gerald's oval A6.

[Bjorn Jonsson]

Here's everything from image 110 ("String of Pearls" plus more) processed from the raw framelets. First an approximately true color/contrast version (small scale features have been sharpened a bit, partially simply to compensate for all of the resampling steps during processing):




And then a version of these images where the effects of global illumination have been removed and the contrast, color saturation and sharpness exaggerated:



Most/all of the features here are also visible in image 109 posted earlier by Roman but the resolution of that image is higher. As mentioned earlier it might be possible to use images 109 and 110 as a stereo pair.

Juno's altitude was ~20,000 km when the image 110 framelets were obtained. The processing is more or less identical to what I did when I processed a PJ-4 image some time ago.

These images reveal lots of interesting features, some of which are relevant within the context of the interesting Jovian weather/clouds discussion above. "String of pearls" oval A6 is visible. I find the circular storm SSW of oval A6 particularly interesting. Cloud shadows are visible within it and elongated, elevated clouds within the storm apparently form a spiral.

[Gerald]

Outstanding work, Björn!
I didn't yet include full illumination adjustment into my renditions, but am curious how those results will eventually compare to yours. One to three CPU cores are running almost around the clock. So, it will take another few days, before I've completed all "straightforward" products, and find time to dig a little deeper into the data.

I've tried the 109 / 110 pair as stereo, and am not yet quite sure, whether a 3D effect is perceptible. There is also some risk to confuse cloud motion with parallax.

Here some of my "straightforward" products:
PJ05 Approach Movie (and cropped close-ups), level 1, decompanded stills. All images rendered with the same set of parameters (best for distant images), therefore some of them may not be perfectly rgb aligned.

[stevesliva]

Some quite nice crescent/quarter shots in your stills, Gerald!

[scalbers]

I've tried the 109 / 110 pair as stereo, and am not yet quite sure, whether a 3D effect is perceptible. There is also some risk to confuse cloud motion with parallax.

The blinking animation Gerald posted earlier was useful to look at in the context of seeing things in 3D (as a complement to an anaglyph or side-by-side pair). I think it could show some parallax if it is registered more closely. I suppose the risks would be mainly the cloud motion in a rotating spot, or some type of vertical wind shear in a jet region. Other more uniform movements could be compensated for.

[Gerald]

Departure sequence, level 1 stills, decompanded, some overlap with approach sequence, but slightly different parameter settings.

Most of PJ05 "straightforward" processing completed. Time to work on enhancements, movies, advanced data reduction software, may be another attempt to create stereo products.

[Jerry]

What is the circular cloud formation in this image? Is it just an artifact of processing, or is it something real?

Thanks.

[Bjorn Jonsson]

This is definitely a real feature, it appears in more than one of the source images (framelets) used to make the final image.

[Jerry]

This is definitely a real feature, it appears in more than one of the source images (framelets) used to make the final image.

I don't know if it's possible in a gas medium, but it almost looks like a complex crater.

[nprev]

It's not possible. It's a complex low or high-pressure center, more likely the former.

[Roman Tkachenko]

Jupiter at 6000 km

[scalbers]

It's not possible. It's a complex low or high-pressure center, more likely the former.

There are also some ring shaped IR features in the image I posted in post #37, though I'm unsure if they are analogous.

Very impressive image Roman - looks like a closer view of some convective systems in the upper right.

[JRehling]

Wow, Roman. In the upper right, there are patterns that crisscross, apparently because a higher cloud layer is translucent and details at two different levels are visible. Unless that's an illusion, that is a very powerful sort of detail, and I don't recall ever seeing something like that in visible light Jupiter imagery before.

[Spock1108]

Roman congratulations! A crazy image! What is the resolution of this image? Is Beats images of Voyager and Galileo? I have never seen cloudy structures so clear on Jupiter!

[Gerald]

The "storyboard" version of a PJ05 flyby movie I started to render:

The sequence covers PJ05 images #99 to #116.
The intended final version will be 1280x720 pixels (16x larger than the thumbnail, and rotated by 90 degrees), 12x the number of frames (108.48 seconds anticipated with 25 fps, give or take a few seconds), and enhanced.
Rendering one second of the movie takes roughly one hour, depending on the content. So, I hope, that most of the movie will be rendered, before the next week-end is over, and PJ06 images wait for being processed.

[Bjorn Jonsson]

Polar projection of PJ-05 image #111, and detail, enhanced in different ways:


(NASA / JPL / SwRI / MSSS / Gerald Eichstädt)

What is the exact location of the pole in this image? I'm working on PJ5 image 111 as well and want to include a version with a lat/lon grid but as a 'sanity check' I wanted check I've got the pole at the same (or a similar) position as in your image. I think the pole is at ~(900,155) in your image.

[Gerald]

The pixel position you assume for the pole is within my error ellipse.
I still have a known inaccuracy in my camera geometry, so can't tell the exact pixel position. -- Fixing this is one of my high-priority tasks for the next few days, hopefully...

[Gerald]

This is one of the stills of the movie I'm trying to create:

In the meanwhile, fragments covering 53 seconds are rendered (most of the time with three CPU cores running in parallel).
Approach (#99 to #104) and most of the departure (#113 to #116) are completed. The particularly computer-power consuming close-ups are still to be rendered.

[Gerald]

Here another two stills of more than 2000 in the meanwhile:


These close-ups will move rather rapidly in the 125-fold time-lapse; the stills allow a closer look.
An expected 16 movie seconds still to render. Those will take roughly one day of CPU core time. Distributed on three cores, the movie should be completed tomorrow.

[Sean]

This is looking spectacular Gerald. Looking forward to tomorrow!

[ngunn]

They're beautiful but I'm wodering why all the images are so blue-green?

[Gerald]

Youtube upload of Perijove-05 animation completed.
Youtube refused my AVI version; so I needed to upload a terribly large 500 MB+ MOV file.
However, quality may have suffered a bit in the youtube version.

The bluish-green can be of at least two reasons:
- Jupiter's haze appears to be bluish, especially when seen from acute angles, and near the poles.
- Some portions of some of the images are saturated in the red filter band, resulting in a cast to the complementary color, i.e. greenish-bluish. This risk has been taken, in order to obtain better S/N.

[HSchirmer]

I don't know if it's possible in a gas medium, but it almost looks like a complex crater.
It's not possible. It's a complex low or high-pressure center, more likely the former.

Well, considered broadly, e.g. "cavity, gravity, rebound" it's not an entirely incorrect analogy.

It's just density and gravity and equilibrium; although one is hot rock, the other is hot air....

Complex crater with a rebounding central peak isn't all that different from a summer thunderstorm anvil cloud.

[Gerald]

Here is a link to the AVI version of the PJ05 flyby video, in case you find time to create derived products, or simply if you like to watch the movie in better quality.

EDIT: 2703 png still frames of the movie zipped, together about 1.7 GB (huge!) :
part 1
part 2
part 3
part 4

Note, that the file names between the parts aren't strictly disjoint, however the files are different!

[Sean]

Thank you Gerald. 1.7GB isn't that big!

Here is a still from your animation that I have started to process ...



thanks for sharing your work.

[mcaplinger]

Youtube upload of Perijove-05 animation completed.

This is really very promising. A couple of hopefully constructive criticisms:

1 ) you might consider cross-fading between images instead of cutting. There's at least one place where the cutting leaves you with a disorienting black image, I assume because the image coverage hasn't caught up to the spacecraft position.

2) your processing has become quite excellent except for the color. I'm not sure what's going on with the color but I don't think Jupiter is ever that green. Our missionjuno processing just does an auto white-balance after delambertianing and often leaves blue artifacts near the limb and terminator, but not the overall strong blue-green cast.

[scalbers]

The bluish-green can be of at least two reasons:
- Jupiter's haze appears to be bluish, especially when seen from acute angles, and near the poles.
- Some portions of some of the images are saturated in the red filter band, resulting in a cast to the complementary color, i.e. greenish-bluish. This risk has been taken, in order to obtain better S/N.

I recall some discussion about a greenish cast showing up in the Earth flyby images. Perhaps the red band was saturated there also? Unsure if the haze would have been a factor in this case. Would be interesting to model the expected color of Jupiter's haze and clouds with a scattering code.

Maybe this would be kind of drastic, though I wonder if reducing the color saturation in areas where the red is saturated on the bright end would help? Would this help get a better color balance in low intensity areas? Perhaps this is the S/N tradeoff being mentioned. Indeed the bright clouds should be a good white reference, at least near the nadir if the sun is reasonably high up. It is a challenge to maintain a good color balance with strong contrast enhancement, so perhaps a version with less contrast and more accurate hues would be interesting as well.

[mcaplinger]

Perhaps the red band was saturated there also?

AFAIK any saturation is only happening near the limb in some of the images. Even the nadir portions of these images are greenish in many cases.

There is probably a greenish/yellowish cast to images that have no color correction applied. We've reported the band correction factors in the PDS products but I've never actually validated those so if there's still some residual artifact I wouldn't be surprised. As I say, we're using a simple auto white balance which seems to work all right for Jupiter.

[Gerald]

This is really very promising. A couple of hopefully constructive criticisms:

Thanks! The list of basic image processing components I've been planning since months or even years is shrinking gradually. So, I'm going to be open for suggestions, and if it's just for prioritizing my scheduled tasks.

1 ) you might consider cross-fading between images instead of cutting.

I've an older version of code which blends renditions of two images directly from the raws, but didn't yet find time to adjust this code to the changes I've made for a single raw. I may entirely replace this code by just blending two overlapping sequences.
The decision to cutting has just been a matter of available time. I'll consider your point in my priorities.

There's at least one place where the cutting leaves you with a disorienting black image, I assume because the image coverage hasn't caught up to the spacecraft position.

Yes, that's the main reason. I just guessed the latitude coverage of each image with respect to time. Adding some more frames of #105 before starting #106 would have reduced this effect. I've also changed the software during rendition due to visible numerical jiggering effects and performance aspects, but intruduced a flaw, and another numerical difference between the two program versions. This led to different exposure and illumination adjustment. Eventually the movie became less smooth as it could have been. But rendering it anew would have taken another week, and I fully understood the root cause only lately.
I'm expecting these effects and difficulties to be absent or solved in my scheduled PJ06 flyby movie, since the accoring flaws are fixed now, and we have better latitude coverage.

2) your processing has become quite excellent except for the color. I'm not sure what's going on with the color but I don't think Jupiter is ever that green. Our missionjuno processing just does an auto white-balance after delambertianing and often leaves blue artifacts near the limb and terminator, but not the overall strong blue-green cast.

For this sequence, I didn't auto white-balance, but used your lab values (hopefully corrrectly). The stills for the movie are gamma-stetched with gamma=8 with respect to square-root encoding, hence the 4th power of illumination-adjusted radiometric values. This might enhance a subtle bluish cast to an obvious blue or blue-green hue. Besides this, some portions of some of the images may be saturated in the red band, leading to loss of red, and hence to a green-blue hue. I didn't try to correct saturated color channels. I'm strongly considering, that Jupiter's haze is mostly bluish. This shows up near the limb, near the terminator, and overall within the polar haze disks. I hesitate to adjust color weights by expections what a color of an unknown target should be. Analysing the optical properties of the haze is on my list. (We may discuss this in the context of the talk(s) I'm going to prepare for Riga.)

[Gerald]

I recall some discussion about a greenish cast showing up in the Earth flyby images.

These renditions haven't been properly decompanded, nor weighted according to lab data.
I didn't yet render the EFBs with the best available technique. May be I should put this on my list.

[Bjorn Jonsson]

Planetary colors are a complicated subject and I'm not surprised to see automatic processing that includes 'delamberting' sometimes resulting in strange colors.

What I usually do when I am processing the Juno Jupiter images without removing illumination effects is to multiply green by 1.12 and blue by 2.3 after decompanding. These values are empirical and represent a weighted average from three different methods to color correct the images:

(1) Simply adjusting the color of a global image until it looks 'right' (zones get whitish etc.).
(2) Measuring the color of a bright zone in a higher-res image and then correcting the color to make the zone roughly white (maybe slightly yellowish).
(3) Determining Jupiter's global color from a visible light spectrum and then making the average color of a global image from Juno similar. Here I attempted to account for the fact that the Juno global images show Jupiter from a vantage point that is very different from Earth-based images but did so in a preliminary way and need to do this more carefully.

When I remove global illumination effects (which I do using a modified Lommel-Seeliger function - it works better than Lambert) I select a well lit and fairly big patch in the image that is not too close to the limb. I then compare the color of the patch to the same patch in an image where illumination effects have not been removed. This results in multipliers for all three color channels that I apply to the image. I do this more or less manually.

[Gerald]

For the animation and PJ06 images, I didn't use a documented illumination model, but rougly speaking, it's somewhere between the Lambert and Lommel-Seeliger models. It's a function of incidence and emission angle with some intentional remaining illumination effect for better 3D appearance. It's derived from an averaged brightenss map as a function of incidence and emission angles, and some fine tuning on the basis of PJ05 images.
Thus far, I didn't yet model the dependency of the function from light wavelength. But I've implemented the infrastructure to do so in the near future. This lack of color adjustment to emission angles leads to a bluish cast in much of the animation, since most of the close-up sequence is derived from portions of the original images with acute emission angles, and without adjusting e.g. for Rayleigh scattering. I'm intending to do this in an automated way as soon as analysis and implementation are completed. I think, that it will take another several weeks, so it won't yet be applied to the first version of PJ06 animation, at least not yet fully. I'm expecting spectral effects of scattering being dependent on local atmospheric properties, and I'll try to take this into acount, where sufficient data is available.
For animations with up to several thousands of frames, I don't even try to do this manually, but work immediatly towards an automated solution, despite taking a little longer for the first results.

[Sean]

Some processed stills from Gerald's Perijove 05 animation...







...noticed these clouds sneaking by lower left ...

[Sean]

I processed Gerald's work again for this video...

[Sean]

PJ05_110 via Gerald

[Sean]

PJ05_anim_1369 processed frame from Gerald's animation

[Sean]

More from Gerald's PJ05 animation...




And a 4k wallpaper of the same...

[Gerald]

May be, we should consider a real-time animation with Juno spinning at 2 r.p.m., for PJ7, or an earlier test run?
For this week, however, my timetable is full already with several issues to fix, and scheduled products.

[Sean]

Ha, you read my mind Gerald...already working on it.

[Sean]

An image process update for Gerald's PJ05...

[Gerald]

The subtle striping is my fault. For a video, you don't need that high image quality as for stills. So, I created most of the video with an early test version of the illumniation adjustment that truncated auxillary data to integer values. The subtle striping is the visual representation of this truncation. For PJ06, I rendered the whole sequence with internal double precision arithmetics. Automated brightness adjustment has been rather crude, too, for my PJ05 version.

[Sean]

Some processing & retiming on Gerald's animation for perijove 05...

Click thru for a video

[Gerald]

Tonight, I'll upload a set of revised PJ5 stills, no matter whether I'll be able to compile them into a movie, before.

[Gerald]

Revised stills of PJ05 flyby are online.
I didn't even look at most of them myself. So, no warranty about the contents.
I'll try to find time today, to compile an according movie.
I'm intending to update the site once I'll have derived an MP4.

And here a link to reprojected full PJ05 images, in case I didn't provide the link before.

[Gerald]

A revised version of the PJ05 flyby is on YouTube, now.
The PJ05 flyby was dedicated to polar observations with limited data volume. Therefore only part of the latitudes could be covered in good quality.
For the sake of good polar images, some parts near Jupiter's limb are overexposed a bit in some of the images. Due to the applied radiometric factors and gamma stretch, this shows up as turquoise areas.

[Sean]

PJ05_110 details + portrait