I'm going to choose to be optimistic about PJ49, so with that in mind, I have added previews of JunoCAM's observations of Io for PJ49. Obviously, JunoCAM's real observation plan will likely differ but I added previews for the first and last opportunities to image Io on the pass, a preview of an image nearest closest approach, and one for when Io is near the center of the JIRAM FOV. The observation at closest approach also has the Marduk plume which has a good chance of being observed on this encounter, presuming it is active. The Volund plume might also be visible near the terminator.

The previews use the Voyager/Galileo basemap. The left images were originally projected at the same resolution as JunoCAM but were then enlarged by 5x while the image on the right is the basemap reprojected to 5x the JunoCAM pixel scale.

https://pirlwww.lpl.arizona.edu/~perry/Juno/pj49.htm

Hope this goes well for Juno.

A screenshot of the juno io encounter
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What software is that screenshot from, John?

Just adding a note that I hope to have my preview video out sometime in the next couple of days. Script is done but it is longer than normal so I'll need to sort out what footage/images goes where.

Celestia using the SPICE kernels for orbits
for any that do not know what the spice kernels are here is a link
https://naif.jpl.nasa.gov/naif/index.html

Preview video for PJ49 now up:

https://youtu.be/0ukXRu5bSNs

I'm wondering if the flyby went well?

No images yet... Hopefully this just means that MSSS is performing some extra checks verification steps on the data after the issues they had the last time around, or their pipeline is choking on the Jupiter/Io combo images. Spacecraft seems to be fine as the reconstructed C-kernel showed up Wednesday around noon.

First batch of images including several Io images on missionjuno now.

Thank you much! just saw! You have no idea how relieved I am right now!

PJ49_77 Io, "Long exposure" TDI=6, Adjusted with .4 gamma to show a little Jupiter-shine on night side. Don't see any signs of plumes along limb.
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A quick run of PJ49 Io using JNCE_2023060_49C00076_V01:


Io - March 1 2023

And a run on JNCE_2023060_49C00094_V01 for a look at Jupiter


Jupiter - PJ49-94

My first image processed

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Definitely a pain with some flat field artifact that needed to be corrected. The one in BLU_004 worked fine with my flat field image, but not so with the one in RED_002. That's why Mulungu and Susanoo look red.

Here is a montage of all five Io images.

Original resolution was 34-43 km/pixel but have been expanded by 10x to improve the visibility of features.

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My collection. Nominal and exaggerated processing.
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And I suppose there was something other than Io imaged.
Here's PJ49_100, exaggerated color/contrast. Altitude 20481 km.
"Losslessly" (HUFFMAN) compressed source definitely worth clicking through to full resolution.
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Maybe the orientation of albedo features is coincidental, but it seems like this look at Io is showing a strong specular component in the terrains in the middle of the closest images. I don't know if this has been noted in previous research. It always seemed pretty flat / lambertian to me in Voyager and Galileo imagery. Of course, Io has quite a few different terrain types, has been viewed from various geometries, and is changeable over time, so the whole discussion here could be both complex and lacking in full data.

I think those are just bright areas combined with illumination angles, not necessarily specular reflection. that being said, I should photometrically correct these images first before I am certain about that.

Brian’s stuff has a bit of a preview. the bright, VERY SO2 rich patch in NE Lei-Kung Fluctus apparently is still there based on Brian’s processing.

A montage of the five PJ49 Io images. The viewing geometry is also shown using computer generated images that include a latitude/longitude grid. They are based on a Voyager/Galileo map of Io.

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The images are enlarged by a factor of 5 relative to the original data. The color balance is preliminary. Io's color is a remarkably complex subject - hopefully this is not very far from Io's real color. More on this later.

Isn't that just a roundabout way of saying it's the most colorful and contrastful world apart from Earth.

That's a wonderful thing about Io, but another property of surfaces is the extent to which they show lambertian ("flat") or specular ("mirrorlike") characteristics, which can itself vary by wavelength; the potential complexity is extraordinary. The Mariner 10 images of Mercury, which is one of the less colorful worlds, overall, led to research by Bruce Hapke and others on the reflectance properties of its surface, which might have seemed like an empty topic given its similarity to the Moon, but it wasn't.

With Io, and the fact that new surface of different types is deposited over time, it may not even be possible to characterize the general issues in a lasting way.

With relatively little variation in illumination angle in these (nonetheless wonderful PJ49) images, it may not be clear how much we're looking at some really bright surface, or some specular surface that would look less bright from another angle, and JunoCam's performance is itself variable, so we may be left wondering why the brightest areas here look so bright.

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Uploading a new version that deals with the artifact in JNCE_2023060_49C00076_V01 much more elegantly. There is a large splotch in the flat field for the red filter at sample 1194, line 43 that I've always had a hell of a time removing. The splotch seems to be in a different spot compared to its position in PJ34-PJ35. I created a new flat for red using Jupiter images from PJ49 and that cleaned it right up so Susanoo and Mulungu no longer look red.

To create my flat, I utilized images of Jupiter from PJ49 where Jupiter fills the field of view for at least some of the frames, so for example JNCE_2023060_49C00105_V01 and JNCE_2023060_49C00104_V01. I used cubeit and cubeavg to create a single image that is the average of all of 44 frames. I need to remove the gradient caused by illumination conditions on Jupiter. So first I take a copy of that average image and I null out all the splotches seen. I then shrink the image to a full-width, single line then expand it back out to full size. This creates an image with just the gradient. Then I ratioed the average image with this gradient image. This has the effect of removing the gradient and normalizing the image.

Not the best flat for large-scale gradients in the detector since I'm effectively filtering them out, but does a good job in dealing with the splotches.

Okay, I’m not sure that the RED band splotch moves due to time. For example, the same splotch can be seen in a PJ43 image of Io and in the same spot as PJ49. I tried processing the RDR data released to the PDS for PJ43 today and I tried creating a flat using RDR data from PJ43 and the splotch was not in the same spot, about a line up. this is the same as the flat I created from PJ34 data.

Best I can tell, the characteristics of this splotch differ depending on jno:TDI_STAGES_COUNT. The Io images seem to use 2 while most Jupiter images use 1, except for the PJ49 Jupiter images.

If any of you know, maybe Brian?, of any Jupiter images where jno:TDI_STAGES_COUNT=2 and where Jupiter fills the field of view and taken prior to PJ43 so that RDRs are available, please let me know and I can create a flat from them.

That would be curious if a splotch in the flats moved; it would be a question of the origin of the splotch. Any permanent change in the optics or sensors would seem to remain in place. Something due to stray light (is Jupiter a possible source?) could move. A thermal excess that excites the sensors might move, depending on the origin.

I guess so. The problem seems to be that the color of processed Io images apparently is very sensitive to the exact camera filter properties - far more so than when processing images of Europa, Ganymede or Callisto. For example the red terrain (e.g. the red 'ring' around Pele) isn't obvious in Voyager images processed in a 'normal' way where an orange filter is used as red (it is visible with extreme processing though, see e.g. this thread). The problem is that these reddish areas start to get brighter relative to other terrain when you use a red filter instead of orange and they are even brighter in the near-infrared. This brightening relative to other areas has barely started at the wavelength of orange light.

The JunoCam filters are different from the Galileo filters. There is a blue filter (Galileo had violet) and the JunoCam red filter bandpass is 600-800 nm (i.e. into the near-infrared) with an abrupt cutoff at both ends. The CCD is sensitive to light in this wavelength range. This is different from the Galileo red filter. It is apparently impossible to make Io's color in the JunoCam images very similar to Io's color in the Galileo images by simply combining the R/G/B channels into a color image. Colchis Regio turned out greenish if I made the average global color roughly identical to the global color of the computer rendered images I posted earlier (in these computer generated images I attempted to correct the color by using synthetic blue instead of violet). If I make Colchis Regio roughly gray I 'lose' most of the yellow color in areas that are yellow in the Galileo images. If desired, it might be possible to 'fix' this using channel mixing, possibly by making a synthetic red image as some a weighted average of the red and green channels.

It will be interesting to see JUICE's images of Io. Its camera has red, green and blue filters (it has a total of 14 filters). But it's also going to be interesting to see data from the MAJIS instrument. It is an imaging spectrometer that covers wavelengths from 0.4 to 5.7 µm by simultaneously collecting 480 spectra. If I understand correctly the highest resolution for Io should be something like 50-100 km/pixel (take this with a grain of salt). Not exactly high resolution but enough to be very useful for getting a better idea of exactly what Io's color looks like to the human eye.

This is image PJ49_105 in approximately true color/contrast and enhanced versions. North is to the right and slightly up. Several haze bands are visible in the enhanced version. The central area of these images is at planetographic latitude ~65 degrees north.

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The next image following this one at the missionjuno website is image 123, i.e. images 106 to 122 seem to be missing (assuming that the difference in image numbers is always 1 for adjacent images).

In the PJ48 images, the reddening trend of the JunoCam images greatly accelerated (see the PJ48 thread). Interestingly, the reddening in the PJ49 images apparently has reverted back to the trend before PJ48. The PJ49 images actually seem to be *less* red than the PJ49 images. There are some sources of errors and uncertainty (in particular few images at PJ48 and no northern hemisphere PJ48 images) but this seems pretty certain nevertheless. Below is an updated plot showing the color correction factors I'm currently using for every perijove.

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This is different from a plot I uploaded back in 2021. There I was measuring the blue/red ratio in raw images with no processing except for decompanding. Here I am interested in the color correction necessary after decompanding, flat fielding and dark current correction. Actually the flat fielding and dark current correction results in only a tiny change to the blue/red ratio (or in this case the color correction). The color correction is in % with e.g. 275 for blue meaning that I multiply blue with 2.75.

Here the measured multiplier for blue is 4.5934 at PJ48 and 4.3315 at PJ49. These values are averages from several different measurements. Even if I selected the lowest values I got for PJ48 and the highest values I got for PJ49, the PJ49 images are less red (these values are 4.55 for PJ48 and 4.42 for PJ49). In the image above, the PJ48 value is abnormal enough that I didn't include it when computing the Bezier curve.

It is very interesting that this increase in red relative to blue occurred following a JunoCam anomaly at PJ48. Maybe it is even more interesting that the PJ49 images are less red than the PJ48 images; this is very unusual as the graph above shows.

In addition to what's discussed above the data above suggests the following:

(1) The reddening probably didn't start until sometime after PJ20 (possibly at PJ22 or PJ23).
(2) This reddening trend probably accelerated near or following PJ40 (it is not clear exactly when but the trend when looking at several PJs around PJ40 suggests this).

Yes, splotches change location in the data as TDI changes.
Unfortunately, when I went looking some time ago, I didn't find a good set of TDI=2 images that covered the full frame from which to produce TDI=2 specific flats. Instead I developed a method to smear my good TDI=1 flats for use at higher TDIs. But it doesn't work very well. 🤷

Okay, I will just have to be patient. They will come in PJ49. It just means that I will skip processing one of the Io RDR images from PJ43 that hits that same splotch until the PJ49 comes down.

Very interesting, Bjorn.

Your comments on the further anomalous details of the reddening (eg, the effect being greater in PJ48 than in PJ 49), as evidenced on the blue line, seem also to appear, to a lesser extent, on the green line. One might try to verify this statistically, and narrow the number of degrees of freedom at work.

This is probably grasping at straws, but I wonder if there is any additional feature in any of the images that might constrain the source of the effect. Eg, do Saturn, Earth, Sirius, etc. ever appear as a background object that could measure the effect on another known reference object? Given that Ganymede was too small to serve in that capacity, I guess anything outside the Jupiter system would also be hopeless in this regard. Io, on the other hand, has now appeared in multiple PJ imagery, but has its own remarkable variations in color that might disqualify it for the purpose, unless the same terrain has appeared several times.

New departure movie using frames taken from March 1st to March 20th. Unfortunately the Galilean Moons are hardly visible and, when visible, aren't more than a pixel in size.

YouTube:
Jupiter - Perijove 49 Departure Movie

From the BAA Jupiter Section Juno PJ49 report:


I haven't seen anything official about this yet though.

I guess I haven't been paying enough attention, because I don't know what "the N4 domain to the SEBn" means. Some googling and forum searching didn't find anything.

I'd be grateful if someone would explain.

The Jupiter community loves their acronyms and rarely bothers to explain them any more. N4 ("northern northern northern northern") https://britastro.org/section_information_/...3-to-n6-domains is the middle part of latitudes 43 to 64ºN. SEBn is "a superfast prograde jet at 7S" https://britastro.org/jupiter/epsc/EPSC2011...ct-SEBn-jet.pdf -- I think SEB is southern equatorial belt, n is the northern part?

I've complained about this (to my mind obscure) nomenclature to the point of being obnoxious, but you have to call stuff something and this is traditional.

Thanks Mike!

And thanks especially for elegantly providing references in context.



"[N]orthern northern northern northern" gets points for whimsy. Also, in my experience the annoyance to outsiders of obscure jargon is balanced by the satisfaction it gives to insiders when they sling the bat, thus preserving felicific equilibrium.

These BAA reports assume that the reader is familiar with the belt/zone nomenclature. It is explained here (includes a nice diagram):

https://britastro.org/jupiter/programme.htm

Lots of acronyms. The "B" at the end of an acronym means "belt" (they are dark) and "Z" means zone (they are bright/whitish). A "T" means "temperate" and "Trop" means "tropical". So e.g. SSTB is the "South South Temperate Belt". The width and color of the belts/zones varies though and sometimes the narrow ones disappear temporarily even though the zonal wind speed at the relevant latitudes doesn't change when this happens.

There is also some interesting information here: https://britastro.org/jupiter/guide.htm

It doesn't seem that much more complex than the permanent features we humans can attach names to on solid bodies.
Earth's meteorology divides the planet in a similar fashion, and we even name large storms that never lasted as long as the GRS/Oval BA.

Bjorn, thanks for those helpful links.

And continual thanks to you and all of the experts and specialists here for sharing your work on UMSF.

Mike,
Can you say if there is an explanation for the increase in "noise floor" between
JNCE_2023075_49C01628_V01-raw.png "IMAGE_TIME": "2023-03-16T21:00:30.042"
and
JNCE_2023075_49C01632_V01-raw.png "IMAGE_TIME": "2023-03-16T22:00:27.920"

Plot of mean of raw values. The above times corresponds to the discontinuity on the right.
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Those scalloped-shaped changes look like the change in temperature that results when a new level of heat is applied/removed and a system adjusts to the new stable temperature.

Kepler, as an example, had noise driven by temperature, and as the spacecraft changed configuration, and the heating of different parts of the spacecraft by sunlight began or ended, the sensors had noise levels adjust to that change. However, that happened very intermittently with Kepler, which had stable pointing for ~90 days at a time, while Juno is spinning and the geometry is changing constantly.

However, "looks like" is just suggestive, not an explanation. And as for the abrupt jumps, those look like a different beast altogether. Note that when Juno approaches Io, it is also approaching radiation belts and the Io flux tube, so there's potentially a lot going on that can excite electronics.

I don't think it's necessary to call me out by name. Others may have answers and it just makes me feel bad if I can't respond.

As Stargaze has correctly intuited, these are temperature-related and intentional. I can't say more, but one might search for phrases like "radiation damage" and "room-temperature annealing". Once the PDS volume has been released, it should be fairly obvious what's going on.

Earlier in this thread I posted a plot showing the color correction multipliers I was using for each perijove. Here is an updated version where PJ50 has been added. It looked interesting to me and looks even more interesting after reading several of the preceding posts.

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The images now appear to be getting *less* red after a more or less continuous reddening trend since ~PJ20. The PJ50 values are preliminary though and based on only a single image, image PJ50_53. I will be examining more images and this might result in slight changes to the PJ50 values here but I will be very surprised if there are any major changes.

I don't know if the red channel is now getting darker or if the blue channel (as well as green) is getting brighter but it should be possible to determine this.

Image PJ50_53 has a 3.2 msec exposure time whereas image PJ49_91 (a comparable image) has a 6.4 msec exposure time. I don't think this is a significant factor but cannot rule it out yet.

Absolutely not my intention to make you feel bad. My wording was intentional. "Can you say...". A response of "I can't say" is perfectly reasonable and understandable if what I observed was some anomaly which you aren't able to discuss due to project/corporate policy/practice.

I can fully appreciate not being able to talk about certain work-stuff.

However, I didn't know if my observation was an anomaly symptom, an exercise in adjusting gains/CCD-voltage or possibly some environmental (radiation/magnetic field) effect that could now be observed with this unusually long duration and distant image sequence.

There is no adjustability of gains or CCD voltage in Junocam. About the only thing that can be controlled, to some degree, is the camera head temperature. From the Junocam paper:

https://www.missionjuno.swri.edu/junocam/think-tank?id=80

These images are really challenging to process but it should be possible to get useful results in all areas where at least one color channel has useful data, at least if it's red or green. There are of course the 16x16 pixel blocks of bad data that I will probably set to black (hopefully automatically but I'm not sure it's possible for all of these blocks).

Another nasty problem is that there are some blocks of good data that have 'moved' from their correct location. This is most obvious near the limb (from PJ49_107):

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There are also obvious problems where the limb is not visible. Here something strange is happening in the red data (from PJ49_107):

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Most of these problems can probably be fixed be moving these blocks of pixels to their correct location. However, this is a lot of work if it has to be done manually. I doubt it is possible to automatically determine the correct location of these blocks of pixels. It might be possible in some cases where the limb is visible though.

Oh, man, is that some gnarly data. I made a quick attempt at the easiest one (JNCE_2023060_49C00113_V01), making liberal use of inpainting to replace the glitched areas and the enormous quantity of noise.



Jupiter - PJ49-113