The unlit side of the rings Options

[Bjorn Jonsson]

Cassini has previously imaged the unlit side of the rings but now it is doing extensive observations of the unlit side. For the first time in its mission Cassini is spending a significant amount of time north of the ringplane - earlier it has done so only near periapsis but this orbit is different.

This is a quick RGB composite I did from wide angle images:



I made no attempts to correct the color - this is probably not very far from the true color of the rings. Large color variations are apparent, the C ring and the Cassini division appear much more bluish than the thicker rings (A and B ). It should be noted that these images were very probably downliked with the 12 -> 8 bit encoding which basically means that dark areas appear too bright in this image because I did not correct for this.

It's also interesting to compare this image to Voyager images:

Voyager 1: http://photojournal.jpl.nasa.gov/catalog/PIA02241

Voyager 2: http://photojournal.jpl.nasa.gov/catalog/PIA01955
Voyager 2: http://photojournal.jpl.nasa.gov/catalog/PIA01389

[alan]

The rings about a quarter of the way up form the bottom of this image look distorted.

http://saturn.jpl.nasa.gov/multimedia/imag...2/N00064487.jpg

[dilo]

Alan, I cannot see the distorsion... exactly, which rings and how they are distorted?

PS: thanks for great unlit side view and the beeatiful animation, Bjorn!

[helvick]

Alan, I cannot see the distorsion... exactly, which rings and how they are distorted?

I can see it but to me it looks as if the rings have quite a rough texture - it's almost as if they were drawn by someone with a fairly heavy brush action.

[dilo]

I can see it but to me it looks as if the rings have quite a rough texture - it's almost as if they were drawn by someone with a fairly heavy brush action.

Perhaps you're referring to the disuniformities visible as small hue variation is this RGB version (with enhanced saturation):
(start images N00064483/84/86)
Anyway, is something barely visible to me...

EDIT: just posted a short movie showing spokes transit in this region during previous day, the rough texture noted by alan seems to co-rotate with spokes...


I made the following mosaic of 3 images showing the A/F rings with Saturn shadow:
(start images N00064408/09/17)
I like it...

Finally, did someone noticed this very odd image?
http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=80270
Image explainations refers to "SATURN-ERING" but I suspect that this bright strip is another piece of main rings, partially eclipsed by saturn shape + shadow... other ideas?

[ugordan]

Finally, did someone noticed this very odd image?
http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=80270
Image explainations refers to "SATURN-ERING" but I suspect that this bright strip is another piece of main rings, partially eclipsed by saturn shape + shadow... other ideas?

Enceladus or Mimas (at around 90 deg phase) entering eclipse while the camera is staying pointed at the rings?

EDIT: Geez... apologies for the triple post, I assumed the board sw would automatically merge them when posted on a short timescale.

[pat]

[quote name='ugordan' date='Aug 1 2006, 11:21 AM' post='63268']
Enceladus or Mimas (at around 90 deg phase) entering eclipse while the camera is staying pointed at the rings?

The streaked satellite is actually Janus. Thats a very long exposure image (100-200 seconds) tracking some point in the ring plane. The raws site is listing the target as E ring probably because thats the target model used for the exposure calculations. The camera command (ioi) files have two entries for target, 'TARGET_DESC' and 'TARGET_NAME' . TARGET_DESC is supposed to describe the object the image exposure was calculated for while TARGET_NAME indicates the object/position that the camera is actually tracking. Often these are the same, but not always. Its the TARGET_DESC keyword that makes it into the description on the JPL raw site.