Juno PDS data Options

[elakdawalla]

There is now PDS-format JunoCam cruise and Earth flyby data available; it's been submitted to the PDS, but MSSS has gone ahead and posted it on their website. I've created an index page to it here. Unlike my usual index pages, there aren't any thumbnails because of the odd nature of JunoCam images, with their long skinny shapes and interleaved framelets. I haven't played much with these data because it's a bit beyond my skill -- I look forward to seeing what any of you can do with it.

[Gerald]

This one is mostly about finding blips used as star candidates.

After some correlation analysis, it turned out, that hot streaks in the EDRs behave sub-additionally, as expected for square-root encoded data. But squaring didn't result in perfect additivity. The inferred contribution of the hot streak still showed dependence of the background brightness:

Nevertheless I've subtracted repetitive patterns on dark background in a linear way, by subtracting the squares of values obtained from the EDRs, in order to obtain a 0th degree approximation for cleaned images. Blink gif before/after cleaning:

This imperfection is to some degree intentional to encourage at least some resilence of the consecutive processing.

The next processing step tries to find blips which are good star candidates. The centroid of the blips (using pixels above some threshold) is determined after subtracting the mean background level in a ring around the blip.
Then a best-fitting line ("principle component") through the centroid is determined. With TDI 80, stars form small streaks.
After calculating the vertical and horizontal mean distance of the pixels of the blip, weighted by brightness, blips similar to hot streaks are filtered out (some resilence with respect to hot streaks). The remaining star candidates are marked by a respective circle.

I've then roughly compared the marked blips with star maps by eye, to get a preliminary assessment of how many stars can be identified for a good geometric calibration.
For image JNCE_2014038_00R117_V01, a 180 degrees panorama, I could find about 80 good star candidates. Here an according annotated intermediate processing step:

Some similar images are available. This should be sufficient to calibrate at least the red filter area geometrically.

Next, I'll probably simulate BSC stars with two families of geometric camera models, a purely radially Brown-Conrady-distorted pinhole model, and a purely radially Brown-Conrady and hyperbolically distorted pinhole model. I'm expecting the hyperbolic model to be better suited, since a Brown distortion allone cannot model a hyperbolic distortion, if my draft calculations are correct. But I currently think, an idealized rotating pushframe camera should distort hyperbolically. A full radial Taylor series, not skipping any second summand as in the radial Conrady model, might be a third option. The latter approach is sufficiently powerful to describe hyperbolic distortions, as well.

Btw.: JNCE_2014038_00R116_V01 probably shows a gcr hit: