[X] My Assistant

[mcaplinger]

First group of images, including Ganymede, now on missionjuno. More to follow.

[Bjorn Jonsson]

Thanks. A crude way to estimate the radiation dose might be to count spikes/bright pixels in the images.

I'm still wondering about scattered light. I suspect it might be possible in theory to construct a 3D model of JunoCam and the spacecraft components that directly or indirectly can scatter light into the camera and then use some sort of ray tracing to construct an accurate model of scattered light, including its color, for each image. I imagine this would be extremely complicated and a lot of work to do and the practical value limited since it is usually rather trivial to determine the approximate correction per perijove required to process the raw images into approximately true color.

Not necessarily a good metric, but an easy one to produce...

Here are color ratios from the per-perijove Radiation Trend Monitoring datatakes.
The ratios are of the 20th, 200th, and 2000th brightest decompanded (but otherwise unmodified) value
from each color channel.

Did you take into account that parts of these images are usually overexposed/saturated?

I ended up multiplying the red values by 1.0, green values by 1.27 and blue values by 3.05 to correct the color of the PJ35 images. This is a part of image PJ35_57 in approximately true color/contrast and enhanced versions:

[JRehling]

I'm still wondering about scattered light.

I've dealt with scattered light far too often in my astrophotography and one thing that's always been true in my experience is that it is never isotropic across an image, but varies in ways that leave it visible, even if often hard to correct for.

JunoCam images of Jupiter are, in that respect, like a terrestrial telescope's experience of the Moon, which fills much/most of the FOV and can bleed a lot of scattered light outwards. The thing it, that produces ghosts in the blackness around the Moon, but usually has minimal effect in altering the image of the Moon itself because it is of a second order of brightness far below that of the primary image itself.

Perhaps an interesting test here would be Ganymede. Do the images of Ganymede (Io, Europa) taken before 2021 show a different color balance than the images from 2021? The lesser resolution should not be an issue here. And any geometry regarding sources of light outside the FOV would be very different for Ganymede pointing than for Jupiter pointing. Any change in the imaging hardware itself would affect all targets.

[mcaplinger]

Perhaps an interesting test here would be Ganymede. Do the images of Ganymede (Io, Europa) taken before 2021 show a different color balance than the images from 2021?

Bjorn did this already also, upthread. I would prefer to do it for Europa, but don't have convenient tools to identify photobombing moons.