Uranus System Imaging Options

[machi]

I finished my first good image of Uranus.
Planet is colorized from three filtered images (orange, green, blue).
Slightly brownish color of rings is entirely artificial.

Attached thumbnail(s)

 

[Bjorn Jonsson]

Here are two versions of an image from a stack of 8 violet filtered images:



As before the left one has been processed with a combination of a contrast stretch and an unsharp mask and shows both the large scale brightness variations and small scale details although some detail is lost near the limb. The right one was processed with a high pass filter and then an extreme contrast stretch. This largely suppresses the large scale brightness variations but should show small scale features a bit better, at least in the areas near the limb that are dark in the left version.

These images are not from the same sequence of images as the orange/green stack I posted yesterday so the viewing geometry is different and Uranus has rotated around its axis between this image and the orange/green image. The source images here were obtained over a period of 5 hours from January 16 1986 19:51:10 to January 17, 1986 00:51:58.00 when Voyager 2 was 10 million km from Uranus.

The polar cap is now more obvious and this image also reveals that it is very probably circular; its vaguely pentagonal/hexagonal shape in the orange/green stacked image is probably not a real feature. There are also some hints of at least one narrow dark cloud belt a little outside of the polar cap, approximately at latitude 75 degrees south.

These images aren't exactly photogenic but despite that, this has been one of the most interesting image processing projects I have ever undertaken. Especially the orange/green stacked image shows some features I have not seen before in the Voyager 2 images of Uranus. Comparable features (plus many more) have now been imaged with far better clarity with groundbased telescopes but it's still interesting to see some of these features in these old images.

I have also been experimenting with bigger stacks but unfortunately I have now found that stacking images obtained over one Uranus rotation or more does not work well, even ~10 hours apparently does not work very well. This means that significantly bigger stacks than I have been using here are probably not possible although testing this further might be worthwhile.