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Rev 120-121 - Oct 23-Nov 30, 2009 - Enceladus E7, E8
scalbers
post Nov 22 2009, 02:33 PM
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Astro0 quote: Here's the artists view. <<<There's your clue right there!

Wonderful - as I wondered how this might look in color. Is this from multi-color imagery or somehow colorized? I did see some color filter images are available.

One "analysis" type of thing that can be done is to apply a mapping transformation to the image(s) so we can see where the source regions are (by comparing to the map of fully lit images). I'll see if I can give this a shot.


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JTN
post Nov 22 2009, 02:57 PM
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QUOTE (john_s @ Nov 5 2009, 03:48 AM) *
I also don't believe there were any significant pointing anomalies due to the plume passage. There should be an announcement soon about the decision regarding the use of thrusters on orbit 130- I'll check if we're allowed to talk about it here :-)

The "Insider's Cassini" that ngunn linked to seems to have answered that:
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Data from E7 actually allow us to baseline the E9 flyby on reaction wheels instead of thrusters.
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tfisher
post Nov 22 2009, 03:44 PM
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I wonder if we might spot sun dogs in the backlight plume images, if we look in the right spot? Water ice crystals give a refraction halo at about 22 degrees. (see e.g. explanation here). Can anyone good with orbit/camera geometry identify if this angle is covered in the Enceladus imagery?
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eoincampbell
post Nov 22 2009, 04:25 PM
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From these images, would the Cassini team (or UMSF team!) be able to discern if the plume activity has intensified since E6?
Looks... so... alive... smile.gif


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Guest_Sunspot_*
post Nov 22 2009, 04:33 PM
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Guests






sad.gif I think i'm Stereo blind sad.gif

Been staring at the stereo pairs posted here and on the Planetary Society website to no avail.
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ugordan
post Nov 22 2009, 04:48 PM
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Tfisher, keep in mind the FOVs of Cassini cameras are 3.5 and 0.35 degrees so without knowing the exact geometry it would be rather difficult to determine whether a halo ring (I'm thinking no sundogs as the particles here are in freefall) crossed a certain image. Obviously, such a halo ring would be pretty diffuse and wide even in wide-angle images and with localized plume emissions I'm not certain how obvious it would be.

One last image from me, this time (yet another!) soft colorization of what has to be my favorite shot of the encounter, N00146847. Just enough to not make it look grayscale, but not to overdo it for realism's sake.
Attached Image

The foggy appearance of the scene with the moon's limb cutting sharp shadows across makes it somehow look less alien and more familiar, down to earth.


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scalbers
post Nov 22 2009, 05:31 PM
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QUOTE (scalbers @ Nov 22 2009, 02:33 PM) *
One "analysis" type of thing that can be done is to apply a mapping transformation to the image(s) so we can see where the source regions are (by comparing to the map of fully lit images). I'll see if I can give this a shot.


Here's a mapped version of a plume image at 2K map size. The next step might be converting to polar and blinking on top of the hi-res map. I'll also try this with larger map sizes.

Attached Image


Steve
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Poolio
post Nov 22 2009, 05:43 PM
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I'm late to the party and I have nothing to contribute, but I just can't let the opportunity pass without registering my awe at what I am seeing here. I am stunned. My sincerest thanks to the Cassini team and to all of you for producing these amazing aritifacts.
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ngunn
post Nov 22 2009, 06:47 PM
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QUOTE (ugordan @ Nov 22 2009, 04:48 PM) *
my favorite shot of the encounter, N00146847.


Mine too, and that's a great version of it Gordan. I like the way the curved dark limb and the straight shadow edge on the right are clearly distinguishable. The whole thing gives the deceptive impression of being a wide-angle panorama rather than a telephoto shot. It seems to pull the observer right down there into the airy space where the plumes rise like auroras.
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scalbers
post Nov 22 2009, 06:55 PM
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Here's the mapping comparison I mentioned earlier to help locate the plumes on the dark side of the terminator (click to animate):

Attached Image


It's interesting that the forked nature of the left plume appears to have a correspondence with the forked end of Alexandria Sulcus. The more intense spot is where the fork is. The other plume being traced out on the dark side is Cairo Sulcus. Here the really intense spot at the terminator matches a kink in Cairo Sulcus. The original image I used is N146851 so we could in principle proceed to annotate the image with the associated sulci.

Steve
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ugordan
post Nov 22 2009, 07:00 PM
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QUOTE (ngunn @ Nov 22 2009, 07:47 PM) *
I like the way the curved dark limb and the straight shadow edge on the right are clearly distinguishable.

First time I saw it, I thought the shadow is the limb and thought no way, look at that relief!

Steve, is it me or is the plume image noticeably shifted w/ respect to the basemap?


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Juramike
post Nov 22 2009, 07:02 PM
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Nice!


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scalbers
post Nov 22 2009, 07:15 PM
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QUOTE (ugordan @ Nov 22 2009, 07:00 PM) *
Steve, is it me or is the plume image noticeably shifted w/ respect to the basemap?


Gordan - yes I can see a shift in the terrain features too. This is kind of a first attempt at matching the geometry while reprojecting the image. As a quick fix they could be shifted around to fit better - feel free to give that a try. Meanwhile I can see about making some adjustments in the reprojection geometry.

There would be an additional shift in the plumes themselves since they of course are above the surface. One can try and extrapolate them down to the surface if you follow the direction of the eruption.

Steve
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dilo
post Nov 22 2009, 07:34 PM
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Another mosaic joining frames N00146711 and 710 (with deinterlace technique):
Attached thumbnail(s)
Attached Image
 


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scalbers
post Nov 22 2009, 09:07 PM
Post #135


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Update to post #130 plume comparison map with a somewhat better match (click on animation):

Attached Image


Steve
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