Exquisite Saturn Images Options

[Bjorn Jonsson]

Yep, I know where to find them, as I said the image overview page the search thumbnails link to works and contains valid data such as time, target, DVD volume, but the actual *.IMG file download link doesn't work, complains about a server error. I'm not sure, but I think some of these IMGs didn't even show up in PDS searches before so it might be something to look at.
I rarely search the PDS with dates from PR releases anyway, mostly it's by selecting Target Name from the Quick Search tab. I also found the Target List entry on the Adv/Product tab giving me errors every time I enter anything so it's pretty useless now. It would be great if it worked.

If you have Microsoft Access an alternative is to download the database mentioned in this thread. I use it extensively when searching for images. Conversely, I almost never use the PDS search functions.

Regarding these particular images of Saturn where the target name is SKY there is another field, TARGET_DESC containing the value SATURN so that one can be used in addition to TARGET_LIST. I don't even know if it's possible to search by TARGET_DESC at the PDS (as previously noted I rarely use its search function) but the Access database I mentioned contains it plus everything else from the index.tab files.

[ugordan]

Here's a quiz image, can anyone (by anyone I mean NOT you VP ) guess what we're seeing here?

[ngunn]

OK here's my go. The night side of Saturn fills the picture, crossed by edge-on rings mostly also in shadow except at upper right. The rings being lit from below reflect more ring-light onto the lower hemisphere of Saturn than the upper hemisphere. The small moon out in front looks as if it's being illuminated from a direction 30 degrees out of the ring plane which is a few degrees too much to be possible, however this could be an illusion caused by irregularities on the moon. I've no idea which one it is.

[dilo]

Do not know which moon we see in the center, but I suspect we see a small portion of Titan in Foreground (filling lower portion of the frame) and edge-on rings (G ring) on the right... the alignment between the last two elements would be disappointing, indeed.
Beside real explaination, a stunning image! Thanks Gordan.

[ugordan]

Ngunn, that obvious, huh?
Here's the caption I wrote for the image:

This peculiar looking image (somewhat akin to a scene from 2001: A Space Odyssey) was taken on May 12, 2006 with the narrow-angle camera. It shows Mimas' crescent suspended above Saturn's night side. At the time of the image Cassini was orbiting practically in the ring plane so the rings are compressed into a narrow line. The phase angle here is so high (145 degrees) that the rings are almost completely in Saturn's shadow. The only exception is the diffuse F ring which is seen here as a bright streak disappearing into the darkness.

Cassini was rotated so that the sun was precisely to the right side of the image, rotating the north vector to about 10:30 o'clock position. Below the ringplane Saturn's night side is softly illuminated by reflected ringshine. A bit of the northern latitudes is somewhat illuminated as well, by much dimmer diffused ring light.

Mimas' crescent is noticably "dented" at the 2 o'clock position -- caused by the rim of the huge Herschel impact crater.
The faint vertical banding is an artifact of the camera enhanced by the darkness of the scene (exposures of around 10 seconds were needed). Taken from a distance of 2.7 million km to Mimas.

To get a better idea of the context for the image, here's a broader view from the Solar System Simulator (note it shows north on top so it's rotated with respect to this image). Also here's the view showing NAC field of view and an extra-zoomed view of Mimas with Herschel.

[ngunn]

Ngunn, that obvious, huh?

It wasn't obvious. It had me pondering and rejecting various alternatives. The giveaway was that very faint illumination of the upper hemisphere - only visible, I suspect, on a nice bright monitor screen. In fact I found it easier to spot on the thumbnail than on the full screen version, and even then only after I'd decided it must be there.

Please don't make them any harder!

Beautiful image indeed.

[ugordan]

Please don't make them any harder!

Beautiful image indeed.

Thanks. Originally I had the image brighter to better show the northern illumination, but the 2Hz banding became unpleasant so I toned it down to this. It's still massively brightened because with a high S/N ratio the banding isn't usually noticeable. The fact the exposures were in the 10 second range and the banding is still obvious implies this was a really dark scene in reality resulting in a weak S/N ratio.

[Ant103]

Prometheus passing front of the atmosphere of Saturn the 14th of April 2007

Attached thumbnail(s)

 

[ngunn]

That is magnificent - straight into the all time favourites file.

Note similar picture with interesting comments in Emily's TPS blog.

[Ian R]

Just a little something for the photo album:

[Bjorn Jonsson]

Not exactly a crescent image but still a beautiful scene showing Rhea in front of Saturn plus two satellite shadows in the northern hemisphere:



This is a quick composite of images W00029902.jpg, W00029903.jpg and W00029904.jpg obtained on June 15, 2007. The color processing isn't particularly elaborate, I initially processed the composite to make Rhea gray and then adjusted the contrast to make the background space (almost) black. The final step was to adjust the color balance a bit based on 'official' images because I wasn't happy enough with it.

Apparently the blue color in the northern hemisphere is fading. This is not unexpected; the blue color should be gone no later than about two years from now.

Apart from the color it's interesting how different the northern hemisphere appears from the southern hemisphere. The contrast is higher and there are lots of fairly bright 'puffy' cloud features.

[Ken90000]

It is kind of refreshing to be back in the ringplane for a while. Is that a penumbral shadow of Iapetus in the lower right? A quick check of The Solar System Simulator implies that it just might be.

By the way, this is a beautiful image.

Ken

[David]

Apart from the color it's interesting how different the northern hemisphere appears from the southern hemisphere. The contrast is higher and there are lots of fairly bright 'puffy' cloud features.

Is that real, rather than just a result of lower-angle lighting?

Also, is the dark smudge in the Southern hemisphere, about twenty degrees from the South Pole, a cyclone feature like the Jovian spots? Or is it something else?

[Ken90000]

I still support my theory that it is the result of a partial eclipse of the sun by Iapetus as viewed from Saturn's cloudtops. I have no idea how to post an image from the Solar System Simulator here. However, if you view Iapetus from The Sun on 15 June at 6 Hours UTC with the body (Iapetus) taking up 1% of the field of view, you will see it covers the part of Saturn darkend in the image.

Don't hate the newbie.

Ken

[Ian R]

Good stuff Bjorn!



http://space.jpl.nasa.gov/cgi-bin/wspace?t...=1&showsc=1

Looks convincing to me, Ken.

Ian.