Perijove 44 data has started to show up.

Jupiter and Io from PJ44_27. Raw data acquired 2022-08-17T13:00
Click to view attachment

First round of images from Perijove 44


Jupiter - PJ44-29



Jupiter - PJ44-46



Jupiter - PJ44-48



Jupiter - PJ44-50

UMSF sized overview of PJ44 initial downlink images. (Exaggerated Color/Contrast)
Click to view attachment
(Will add link to full-resolution version on missionjuno when it becomes available.)

Ah, so PJ44 has come down on the GRS.
In the PJ43 we noted changes in the recent telescopic views of Jupiter:
http://www.unmannedspaceflight.com/index.p...st&p=258005

No, the reddish thing in the last two images in Brian's overview is not the GRS. It is a very hi-res image of the North Equatorial Belt.

Agree, just the North Equatorial Belt. It's hard to tell, but it looks like the GRS was partly visible hitting the evening terminator during the first approach images (JNCE_2022229_44C00029_V01, down at the bottom limb). The time between that image and the one below would have been around an hour and a half. I'll tell ya, though, I'd love to be wrong and the GRS shows up in the next downlink :-)


Jupiter - PJ44-56

Possible, we took a lot more approach imaging this time than my earlier analysis considered.

I assumed the red-ish spot in the lower left of the first image I posted (PJ44_27) was GRS.
Click to view attachment

Full resolution PNG is at https://www.missionjuno.swri.edu/junocam/processing?id=13572

Here's Brian's last image, centered and sharpened on the putative GRS, with some subtraction of the baseline cloud colors.

That sure seems to be the GRS. However, I don't think that this view adds much to what amateurs are capturing from the ground.

Ah, I see now.
"Wishful thinking"...

But Brian's last image does appear to show a GRS, oblique view, with that white "high cirrus" high altitude collar around the GRS. With proper processing that image could be informative.

--Bill

Mike, can you tell us about PJ44_73 "RADIATION TEST IMAGE"?
It's been a while since I've seen a new image type.

This was companded with the "linear 1" settings, I wanted to see if there had been any significant changes in the black level of the sensor.

[IIRC linear 1 maps 0-255 directly, 256-511 divide by 2, and clamps higher values to 255, because of idiosyncrasies in the logic implementation. ]

Though this entails the obvious wavelength constraints, the current state of the Great Red Spot was captured by the JWST.

https://esawebb.org/images/

Interesting. So is the 102 bias I see in the raw data a "black level" that is normally present but gets subtracted off before companding?

Has the current "black level" been used for the entire mission?

Looking at this, if there was a mode that just kept the lower 8-bits (no div 2, no clamping), I think it could be turned back into a
full range non-commanded image, since Jupiters brightness varies fairly slowly. I think it would "just" need to be phase unwrapped
(something used in interferometric SAR processing.)

PJ44_23/25/27/29 Orthographic view over Great Red Spot

Images PJ44_23/25/27/29 are rendered from an orthographic view aligned with GRS.
From this perspective the GRS is very stretched out relative to the raw image data because of its proximity to Jupiter's limb.
A gamma adjustment was applied to boost contrast.
Click to view attachment

And discovered GRS also visible in a few departure movie frames.

Images PJ44_92/94/96/98 are rendered from an orthographic view aligned with GRS.
From this perspective the GRS is stretched out relative to the raw image data because of its proximity to Jupiter's limb.
A gamma adjustment was applied to boost contrast.
Half an hour separates each image which were acquired between 2022-08-17T22:00 and 2022-08-17T23:30 at distances ranging from 580,788 to 672,801 km.
Last frame (PJ44_98) shows eclipse shadow of Io crossing over (Sun relative) limb.
Coloration shift between PJ44_92/96 and PJ44_94/98 due to longer exposure causing "over exposure" in some image color bands.
Click to view attachment

Jupiter, Ganymede on left and Europa on right - PJ44_45 crop
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Yes, all of our "digital CDS" CCD systems going back to the original MS98 MARCI have had this, it seems to be intrinsic to the CCD output. The DC offset has to be compensated for if you use sqroot companding. You can perhaps find indications of this if you look at papers, the PDS docs for MSL and M2020, etc. hard enough (or not.)



Yes, and this image shows that it is unchanged since pre-launch.


There's a mode like that for MSL/M2020 though AFAIK nobody has ever used it. There's no such mode for Junocam, which uses a piecewise-linear compander instead of a table lookup compander to save parts and logic in the JDEA.

The reconstruction method you describe might work for a smoothly-lit bland object. The TV system on Mariner 6/7 had a "digital video" stream that consisted of truncated samples like these, but the reconstruction method had problems and the whole concept was generally thought to be a bad idea and was never used again IIRC. https://nssdc.gsfc.nasa.gov/nmc/experiment/...id=1969-030A-01

Thanks, Brian. That view was "stuck between the limb and the terminator" and this is about as good as can be done. It does show some of the structure around the GRS.

--Bill

Thanks for the detailed reply.
Fascinating reading about the 1971 Mariner 6/7 image processing in https://www.researchgate.net/publication/23..._and_7_pictures

Honestly, turned out better than I was expecting given how squished-against-the-limb the GRS is in the raw data.

Here's a quick-and-dirty composite of approach and departure GRS images (PJ44_23/25/27/29/92/94/96/98)
Click to view attachment

PJ44 Image Collection Exaggerated Color/Contrast
Click to view attachment
Full Resolution version at https://www.missionjuno.swri.edu/junocam/processing?id=13667

PJ44 Image Collection nominal contrast.
Click to view attachment
Higher resolution PNG version (where moons are a little more visible) at https://www.missionjuno.swri.edu/junocam/processing?id=13668

Still, "squished against the limb" gives a different perspective to the GRS.