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Posted by: AlexBlackwell Dec 9 2005, 09:19 PM

An excerpt from Emily Lakdawalla's blog entry today ("http://www.planetary.org/blog/article/00000305/"):

I'll only add that Cassini has several "Kodak Moments" planned for the tour. In fact, as Cassini Mission Planning defines them: "These images are *candidate* opportunities for aesthetically pleasing images to be taken. Navigation may consider replacing one OPNAV with one of these images, but only if navigation margin and workforce allow. It is expected that on average, about one image per sequence may be implemented, totaling a few dozen over the tour."

The one planned for the S17 sequence is OK, I guess. It's a nearly edge-on shot of the rings with Mimas, Calypso, and Pan in the frame. S18 has two, one of which has Titan nearly occultating Enceladus. At any rate, expect some dazzling shots of the rings later in the tour, when Cassini is in a high inclination orbit.

Posted by: tasp Dec 10 2005, 03:42 AM

How about that. I thought the 'pretty' multiple moons all in one picture were absolutely crucial for precisely measuring the moons positions and Cassini's location amongst them.

Thanx for the deeper insight into the mission planners goals and motivations.

I like those shots regardless of the motivation for taking them.

Posted by: elakdawalla Dec 10 2005, 05:48 AM

Most of the multiple-moon shots are indeed for optical navigation, as you say; but op nav images are usually just taken through the clear filter, and usually are one-off shots. To do a "kodak moment" they typically do RED-GRN-BL1 which allows them to create an approximate true color version. Judging from what I've seen on the raw site those RED and BL1 filters are pretty much only used either when they're specifically composing a pretty picture for public consumption or when they're shooting a full set using all filters for spectrophotometry. GRN gets used all the time though.

--Emily

Posted by: djellison Dec 10 2005, 09:54 AM

The same as MER

You can tell, if they do something with just L456, it's a Kodak Moment. But L257 is normal

Doug

Posted by: JRehling Dec 10 2005, 03:01 PM

It seems to be a bandwidth concern, with just CLR or Green as the default, L257 to get some spectral information (also, varying polarization is a rarer alternative), with the rare full-filter set.

As far as Photojournal-level releases, Cassini has led to a surprising proliferation of BW pictures that seem like a throwback to Mariner after, eg, Viking + Voyager were so heavily color-based in public releases. Well, this is a mission-by-mission issue. But as far as PR goes, they ought to stick with the color releases. It would be nice if one of the occultation event "movies" were done in RGB.

Posted by: Sunspot Dec 10 2005, 03:32 PM

The Moons aren't that colourful though - except Titan. A shot of Titan passing in front of Saturn would be nice though.

Posted by: elakdawalla Dec 10 2005, 04:08 PM

Yeah, it's true, color would be wasted on those movies. And anyway the movies already take a lot of bandwidth because of the multiple frames -- it's hard to justify tripling the bandwidth in order to get color.

I think that the proliferation of BW on Cassini releases may ironically have to do with just how many filters Cassini's cameras have. A great many of them are devoted to methane bands and continuum bands in the infrared and they use those a lot. Combining several of those into color images makes really cool psychadelic pictures of Saturn showing all kinds of incredible detail in the cloud structure but they look "fake" because of all the colors. Black and white views look more "real."

Perhaps we need more people here to use some artistic license to make more colorful Cassini pictures

--Emily

Posted by: pat Dec 12 2005, 10:54 AM

[quote=elakdawalla,Dec 10 2005, 05:08 PM]
Yeah, it's true, color would be wasted on those movies. And anyway the movies already take a lot of bandwidth because of the multiple frames -- it's hard to justify tripling the bandwidth in order to get color.


Its a combination of allocated datavolume and the typical speed of the mutual events. The transits themselves usually don't last longer than a couple of minutes, some only 20-30 seconds or so. With a frame time of 33 seconds it takes 99 seconds to actually take a RED-GRN-BL1 triplet. With the scientific justification for the observations being orbit determination of the satellites its hard to justify three filter sets just to produce colour images especially if you only have enough allocated datavolume to take 10 images. Then there is the fact that the events are so rapid that the satellites are in different relative positions in every single image so you can't just combine a RED-GRN-BL1 set to make a single colour image. You have to 'fake' things and 'cut out' the satellites from the different filters to combine them.

Bandwidth per se usually isn't the issue its nearly always the absolute allocated datavolume for an observation thats the limiting factor.

And one final tid bit about the KODAK MOMENT images. These observations are planned by Mission Planning at JPL and executed by the NAV team at JPL and specifically CANNOT be used for science. All science images are planned and executed by the ISS team, the Mission Planners at JPL have no input to this process and no data rights, until the archived images are released to the general public by the PDS 9-12 months after they are taken. Only members of the ISS team can do science with all images taken by the ISS cameras before this happens (that includes all OPNAV and KODAK MOMENT images).

Posted by: dilo Mar 23 2006, 06:09 AM

This low phase-anghle view of Janus+rings+Titan completeley taken away my breath, I'm still looking for it!
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS19/N00055798.jpg

Edit: Do someone wants to make a good movie with the entire sequence?

Posted by: um3k Mar 23 2006, 06:24 PM

Here are some movies: http://um3k.justinphillips.googlepages.com/janus-rings-titanevent
Let me know if you need gif versions.

Posted by: mcaplinger Mar 23 2006, 07:33 PM

Have they ever taken a large color mosaic of all of Saturn and the rings?

Posted by: ugordan Mar 23 2006, 07:41 PM

http://ciclops.org/view.php?id=483

Posted by: Bjorn Jonsson Mar 23 2006, 07:44 PM

Yes, on October 6, 2004. See coiss_2007\data\1475761489_1475767501

Posted by: AlexBlackwell Mar 23 2006, 07:45 PM

There are a few Kodak Moments for "full portraits" towards the end of the primary tour, especially in 2008 during S39 and S40, when Cassini will be in a highly inclined orbit and looking "down" on the system during portions of its orbit.

Posted by: dilo Mar 23 2006, 09:18 PM

Very nice animations, um3K... I would call it a relativistic work!



Very nice animations, um3K... I would call it a relativistic work!
thanks

Posted by: paxdan Apr 4 2006, 03:16 PM

Looks like another Kodak Moment has just come down in the raws. Here are links to the http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=70003 http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=70002 and http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=70001 images.

Posted by: Dyche Mullins Apr 5 2006, 01:11 AM

I have lurked around this forum for a while and thought it might be time to contribute (a little) something.

Posted by: dilo Apr 5 2006, 06:28 AM

Nice work, Dyche... look also to http://www.unmannedspaceflight.com/index.php?s=&showtopic=2448&view=findpost&p=49057

Posted by: Dyche Mullins Apr 8 2006, 12:46 AM

This probably doesn't qualify as a Kodak Moment but I had fun putting this old image together from the raw data.

I left the edges of the raw images hanging out as a registration test.

Posted by: dilo Apr 29 2006, 08:10 PM

On Apr,28 Cassini taken some beautiful portraits of Epimetheus in front of A/B rings and Titan (already highlighted in http://www.unmannedspaceflight.com/index.php?s=&showtopic=2644&view=findpost&p=52316).
Here below, I report a stitch of two clear-filter images taken in different time in order to have a panoramic view of the rings and a combination of RGB detail of Epimeteus (registration of all objects in the images is impossible due to strong shifts).

Posted by: Bob Shaw May 25 2006, 12:20 PM

Here's a thought:

Galileo captured a few images of Saturn while in orbit around Jupiter; has Cassini captured any images of Jupiter while in orbit around Saturn?

Bob Shaw

Posted by: ugordan May 25 2006, 02:15 PM

Cassini snapped a couple of images through the blue filter before SOI, in May 2004:
http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=13385
http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=13384

Nothing spectacular, I don't know it they were overexposed on purpose or by the raw image histogram stretching function.
This is about the time the earliest posted raw images date back, so that's about the most recent stuff there is.

Posted by: PhilCo126 May 26 2006, 05:56 PM

This is too much ... this is really too much !
( 'famous' sentence from the Voyager era ... )

We're really lucky to be around in this era of solar system exploration, although I would like to view ahead for a century

Posted by: ugordan May 30 2006, 12:19 PM

A rare color image on the CICLOPS site as image of the day. Showing Titan behind the rings : http://ciclops.org/view.php?id=1985

This obviously required a bit of Photoshopping because of the motion between exposures.
It's notable how the rings have a uniform coloring to them when there's a moon in the scene. When we have the classic Saturn & rings shots, the rings turn out all colorful (even distinctly blue) and neat and stuff, but the moons also turn out blue as a consequence. Obviously one of the two different portrayals is wrong - my guess is the latter one, going for the PR impact instead of realism.
This shot definitely looks more realistic to me, if less awe-inspiring.

Some examples of the rings with a moon present:
http://ciclops.org/view.php?id=1818
http://ciclops.org/view.php?id=1590
http://ciclops.org/view.php?id=1527 (stretched color)
http://ciclops.org/view.php?id=1466
http://ciclops.org/view.php?id=1007

Compare those for example to this:
http://ciclops.org/view.php?id=722
Admittedly, http://ciclops.org/view.php?id=483 does look more like the real thing, though.

Sheesh, am I bored on my job or what?

Posted by: paxdan May 30 2006, 02:47 PM

*snort* if you're that bored perhaps you could help me figure out if there have been any images of a moon-shadow on the rings. I've followed cassini quite closely and don't recall any. Would there be any rational for taking such an image if the geometary was favourable?

Posted by: ugordan May 30 2006, 02:57 PM

Currently, the lighting geometry at the Saturnian system is such that no moon can cast a shadow upond the rings there. Practically all the moons (w/ exception of Iapetus and far-out Phoebe) are in equatorial orbits, their inclination is negligible. The season is something like late summer for the southern hemispheres and the equinox is just too far into the future for Sun's angle to be right for shadows of that sort. We'll have to wait a couple of years more for that to happen. Even then, the shadows will be very oblique and elongated, because of the equinox and the fact no moon rises significantly above the ring plane.

Posted by: Jyril May 31 2006, 11:17 AM

Hubble imaged Saturn during the latest solar ring plane crossing and imaged Dione casting its shadow on the rings (see the image http://hubblesite.org/newscenter/newsdesk/archive/releases/1996/16/image/a).

Posted by: ugordan Jun 4 2006, 03:55 PM

A very high phase sequence of Titan passing in front of the rings has appeared on the raw site:
http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=77062
The above image also shows one of the small moons, dimly lit by saturnshine, seen http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS20/N00062238.jpg "touching" Titan's haze.

Posted by: SigurRosFan Jun 4 2006, 05:20 PM

The small moon is known as ...?

Rings behind Titan's Crescent:

Posted by: pat Jun 5 2006, 12:31 PM

Actually these high phase mutual event images show Titan occulting Janus and then Epimetheus.

N00062231.jpg through N00062240.jpg are Janus and N00062241.jpg through N00062243.jpg Epimetheus.

Posted by: SigurRosFan Jun 5 2006, 01:18 PM

Thanks!

Posted by: SigurRosFan Jun 5 2006, 02:36 PM

And here's the complete animated sequence:

- http://static.flickr.com/76/160890889_275b684f4f_o.gif (2.25 MB)

Posted by: remcook Jun 5 2006, 02:55 PM

Very cool!

By the way: what is that thing at ~2 o'clock on Titan's limb? It looks like an artifact but it seems pretty consistent between the frames.

Posted by: ugordan Jun 5 2006, 03:09 PM

That would be charge bleeding on the CCD due to overexposure. It's consistent because pretty much all parameters are constant throughout the sequence -- phase angle, exposure time, filter combo etc...

Posted by: SigurRosFan Jun 5 2006, 03:11 PM

Nice finding. Another moon?

Posted by: hendric Jun 6 2006, 07:58 AM

Titan: The never-crescent moon!

Posted by: ugordan Jun 7 2006, 09:41 AM

http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=77092

It occurs to me that Cassini's current position on a very long orbit, looking at the system from a very high phase angle would be an excellent place to keep an eye on temporal variability of Enceladus' plumes. From what we've seen so far, they're pretty much constantly churning out water.

Posted by: akuo Jun 7 2006, 10:16 AM

Somehow that image seems really freaky. The lighting looks like its all wrong. Encaladus is mostly in shadow, but the moon behind is not (I'm guessing it's Rhea).

Is the moon behind on the other side of Saturn and so more in Saturnshine than Encaladus?

Posted by: ugordan Jun 7 2006, 11:11 AM

Yes, the other moon (I believe it's Tethys) is on the far side, above the sunlit side of Saturn so its Saturn-facing hemisphere receives a lot of saturnshine. Enceladus, on the near side, is above Saturn's nightside and it's thus showing us the hemisphere facing away from Saturn.

Posted by: dilo Jun 8 2006, 09:23 PM

Here I removed most of sensor noise pattern:

In addition to illumination, another hint about Tethys distance is the "fog" effect caused by G-ring, which lies mostly between the two satellites.

Posted by: dilo Jun 12 2006, 10:15 PM

Incredible sequence now in the raw section, with Enceladus passing in front of Titan + rings + Tethys.
Here a spectacular stitch of two pictures (I know, we should have ONE Enceladus, not two... ):

(original images: N00062413+N00062417)
The inset show the enhanced view of Enceladus with plumes!
Below the geometry of view (from space simulator):


And this is EPIMETHEUS transiting in front of the giant:
(original image: N00062411)

(all images were processed in order to reduce jpeg artifacts and improve sharpness/contrast)

Posted by: ugordan Jun 13 2006, 11:34 AM

A perfect example of weird optical effects: http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=77335.

Light from Titan, scattered in the optics, makes Rhea's dark limb look notably trimmed. Shows how you have to be very careful in interpreting these kinds of images.

Posted by: remcook Jun 28 2006, 09:17 AM

Cassini is churning out stunning images like a factory! Here's another one:

http://photojournal.jpl.nasa.gov/catalog/PIA08207

Posted by: dilo Jul 25 2006, 08:20 PM

Absolutely! and http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=2213 is even more impressive... these incredible views strongly recall wildest scenes from best SF movies

Posted by: mchan Feb 15 2007, 03:01 AM

This http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=2483 on the Cassini website is a Kodak moment for Bob Shaw.

Teke-li-li!

Posted by: John Flushing Mar 1 2007, 03:27 AM

Cassini took a picture when it was travelling fairly close to Saturn. To me, it looked similar to some pictures of Earth taken by people on space shuttles in orbit. For that reason, I decided to put Bruce McCandless into the photograph of Saturn.

Posted by: JRehling Mar 1 2007, 05:43 PM

Tons of new Saturn-and-rings pictures today. Check JPL Photojournal.

Check out

http://photojournal.jpl.nasa.gov/catalog/PIA08361

but don't panic... Saturn is still there.

Posted by: AlexBlackwell Mar 1 2007, 05:56 PM

There's a brief http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=725 on the Cassini website.

Posted by: ugordan Mar 1 2007, 07:11 PM

Note a peculiar thing in http://ciclops.org/view.php?id=2588. Bjorn noticed it back in Ian Regan's mosaic that the rings were too bright around the planet's shadow. The feature is obviously real, the question is: how come? Phase angle effects, similar to opposition effect but on the unlit side? Weird...

Posted by: JTN Mar 4 2007, 03:32 AM

(Only tenuously thread-related, sorry...)
Just noticed a satellite shadow on Saturn in the raws (http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=104445, http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=104446, http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=104447, http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=104448). We don't see that very often, although I guess it'll become more and more common as we approach the solar ring plane crossing in 2009.
(Note: some frames were reduced in size in the animation.)

Posted by: ugordan Mar 4 2007, 12:31 PM

Nice catch there, JTN! Any idea which moon that might be? Mimas? Celestia seems to suggest so.
The raws are all a clear filter so the sequence probably targeted this shadow specifically.

Posted by: JTN Mar 4 2007, 02:35 PM

After some noodling about with http://pds-rings.seti.org/tools/index.html, I think that it might be Mimas or perhaps Enceladus, with the images taken over the space of an hour or so around 2007-03-02 17:00-18:00 (Saturn Viewer time, whatever that is).
Unfortunately I don't think Saturn Viewer plots satellite-on-primary shadows (or at least I couldn't get the Jupiter viewer to show any of the shadow transits from NH, where we know the times -- see also http://www.unmannedspaceflight.com/index.php?s=&showtopic=2088&view=findpost&p=41660), and doesn't have a "view-from-Sun" option (just "view-from-Earth").
(This is much harder with jmknapp's http://cassinicam.com/isslookup/ out of action. What happened to Joe, anyway? He hasn't posted in nearly a year.)

Posted by: scalbers Mar 4 2007, 02:55 PM

I'm trying to remember whether Celestia can render shadow transits? It would be able to show the "from Sun" view at least (in addition to from Cassini).

Posted by: Rob Pinnegar Mar 4 2007, 03:28 PM

We'd expect the first satellite shadows to be Mimas and Enceladus, then the other moons from the "inside out".

Hey, speaking of which: Saturn eclipsed Iapetus a week or two ago. I wonder if that means Iapetus' shadow will pass over Saturn (or, almost as interesting, over the rings) in a couple weeks' time?

It'd be a transit rather than an eclipse, and Iapetus will only block maybe a quarter of the Sun's light, but it might be perceptible. Time to get out the Solar System Simulator.

Posted by: nprev Mar 4 2007, 03:46 PM

Hmm...how big would Titan's shadow appear on Saturn? I don't recall offhand ever seeing reports of any surface-based visual obervations of this during equinox, which is kind of odd.

Posted by: JTN Mar 4 2007, 04:13 PM

About http://hubblesite.org/newscenter/archive/releases/solar-system/saturn/1996/1996/16/ Note also the satellite shadow across the rings in the lower image. I'm hoping for similar views from Cassini in 2009.

Posted by: nprev Mar 4 2007, 05:17 PM

OH yeah! Thanks, JTN; 2009 should indeed be an interesting year!

Posted by: helvick Mar 4 2007, 07:14 PM

Yes it can - http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?letter=.&classic=YES&bibcode=1878MNRAS..38..100L&page=&type=SCREEN_VIEW&data_type=PDF_HIGH&send=GET&filetype=.pdf date I could find online - from Dec 25 1877 @ ~5:46.

Posted by: JTN Mar 4 2007, 07:30 PM

That shadow seems rather small for Titan. Titan's radius is about 1/23 Saturn's (excluding atmosphere). I realise there are penumbral effects to worry about, but the Hubble pic above matches that ratio reasonably well.
(Celestia's great and all, but I stopped trusting it for this sort of thing when I saw what a cop-out Epimetheus/Janus were )

Posted by: Stu Mar 4 2007, 07:42 PM

this was the first definite Titan transit of Saturn date I could find online - from Dec 25 1877 @ ~5:46.

I believe an ESA probe took some pics at the time, and they're due for release "soon"...

Posted by: helvick Mar 4 2007, 07:47 PM

JTN,

I see your point - if I run things forward though by about 12 hours I get this which must be Titan then, possibly the timing I got for the transit is wrong or there is some issue with Celestia handling dates back in the 19th Century.

Posted by: volcanopele Mar 4 2007, 07:59 PM

I'm working on a public version of an add-on I've been using that will drastically improve the positions of Cassini and Saturn's moons for the time period of the Cassini mission.

Posted by: JTN Mar 4 2007, 09:49 PM

I think the times Lord Lindsay gives must be p.m. -- xephem says Saturn would have been below the horizon from the UK at 5:46 a.m. (these observations appear to be from Aberdeen).
(BTW, on p98 there's mention of Titan shadow transit observations on Oct 22 and Nov 23.)

Posted by: scalbers Mar 11 2007, 05:42 PM

Greetings,

It appears Helvick has shown that Celestia can render both Titan and at least one smaller satellite in shadow transit. Looking at the case from this month at the appropriate time (Mar 2 1700-1800UT) I was unable to see any shadow transit from Mimas even though it was in front of Saturn as seen in a solar perspective. I used Celestia 1.3.2. The sun centered view also showed Enceladus near that time passing just south of the limb, so it's unclear to me which satellite (Mimas or Enceladus) would have been in more of a position for this type of grazing shadow transit. So I wonder which smaller satellite Helvick was showing and whether Celestia will show shadow transits for satellites as small as Mimas & Enceladus? Perhaps I'll try running Celestia near solar ring plane crossing time and see how the shadow transits look with more regularity.

Posted by: scalbers Mar 11 2007, 06:03 PM

I found on the Celestia forum that at least Iapetus can be shown. If I have this link correct, it should show a 1980 shadow transit from Iapetus where its shadow falls within the rings' shadow. This version of Celestia would not however show Iapetus' shadow on the rings itself. The inclination of Iapetus means its shadow can be less elongated on the rings. I wonder if there will be a similar event in the coming 2009 season?

http://www.lns.cornell.edu/~seb/celestia/gallery-001.html#5a

Posted by: volcanopele Mar 11 2007, 06:03 PM

Here is what I was able to get with Celestia 1.5pre2:

Tethys transit (2009-03-16)

I couldn't see Mimas or Enceladus...

Posted by: helvick Mar 11 2007, 06:37 PM

Scalbers - I used Celestia 1.5 pre release for the screen caps I posted but I also am unable to find the March 2 Mimas shadow so I don't think the newer version is the reason we can't see it. By my calculations the umbral shadow will only be around 60km across so it will be hard to find unless you know precisely where to look and can zoom in appropriately. I'm pretty sure the shadow will be rendered if the zoom level is sufficient but catching it is beyond me at the moment.

This may have been noted before but I found out that the Ciclops team used Celestia to render the views for the http://ciclops.org/view.php?id=2592 while looking for more information on the eclipse shadow rendering.

Posted by: volcanopele Mar 11 2007, 06:43 PM

Yeah, although I have discovered a bug in my custom .ssc file that means that the Titan map isn't displayed correctly on Titan. I think the rotation offset is off, but it is odd to characterize.

Posted by: jsheff Mar 12 2007, 07:19 PM

JTN,

I agree with you. Starry Night shows the Titan transit at 17:53:00 UT on Dec. 25, almost exactly 12 hours later than Lord Lindsay states.

John Sheff
Cambridge, MA

Posted by: CAP-Team Mar 19 2007, 06:40 PM

Same image, but now generated with xplanet:

Posted by: Toma B Mar 20 2007, 05:37 PM

There are 3 new Saturn animations on http://hubblesite.org/newscenter/archive/releases/2007/13. Some old transits animated...nice.

Posted by: ngunn Mar 20 2007, 06:05 PM

Very nice animations, but the captions for 1 and 3 appear to have been swapped.

Posted by: As old as Voyager Mar 20 2007, 07:10 PM

December 2000 seems an awfully long time ago.

http://photojournal.jpl.nasa.gov/catalog/PIA08899

Posted by: HughFromAlice Jul 8 2008, 08:58 PM

Check out video of Carloyn Porco at 8th July New Scientist talking about her favourite images of the Cassini primary mission. http://space.newscientist.com/article/dn14276-rings-dunes-and-geysers-the-best-cassini-images.html

Even though you may have seen these images before it's fascinating to hear what makes them her favourites.

For me - the hi phase shot of the crescent of Titan is something special. The last pic of a back lit Saturn with an eclipsed sun peaking out on the edge of the disc with a clear view of the G ring and E (Enceladus jet created) ring and the blue orb of the earth at 10 o'clock next to the G ring is awe inspiring.

Posted by: CAP-Team Jul 20 2008, 09:39 PM

I was playing with Celestia to find out when Titan's shadow will be passing Saturn when the rings are nearly edge on, so Titan's shadow is bigger than the ring's shadow. Or, better said, when Titan's shadow will fall directly on the rings, which should be a weird sighting.

Unfortunately Celestia can't cast the shadow of Titan on the rings itself, but Titan's passage on 2/3 august should be spectacular! At this time (around 5 am UTC) Cassini will be able to watch Titan's shadow cross the rings from a distance of about 2 million kilometers (phase angle of Saturn is 113 degrees).

Posted by: jasedm Aug 14 2008, 12:09 PM

I don't know if this happened or not CAP-team - I haven't seen any images with the shadow - would have been beautiful though!
Following on the theme of 'Kodak' moments, I've been having a play around with the solar system simulator, and during the very close flyby of Dione on 7th April 2010, there is a great opportunity to catch 'Titan-rise' from behind the moon. Titan will be less than 1,000,000km from Cassini at that time, and Dione less than 5,000km.
I wonder if it would be possible to include a shot in the sequences (perhaps with the WAC rather than NAC at that range)
Here's what it would look like just after Titan-rise:

Posted by: CAP-Team Aug 14 2008, 02:12 PM

That's because it's next year

Posted by: jasedm Aug 14 2008, 02:55 PM

Oops I shall look forward to it then.....

Posted by: jmknapp Aug 21 2008, 12:38 PM

Was thinking it would be cool to see an animation of all of Cassini's ISS activities in a "typical" day--here's the result, for the 24-hour period starting tonight at 22AUG2008 00:00:00 UTC:

http://cboh.org/~jmk/cas0822v2.mpg

It runs generally at 60x real time (1 min = 1 sec), mostly from the point of view of the WAC/NAC cameras, with a little bit of the Ka-band pointing at the end (I think that's for radio/gravity science?).

The CICLOPS http://ciclops.org/view/5210/Rev81 page for Rev81 says this about the Aug. 22 activities:

Posted by: jasedm Aug 21 2008, 02:42 PM

Cool indeed!
Nice work.

Posted by: ugordan Aug 21 2008, 03:02 PM

Cool video, Joe. The Ka band pointing is most likely a data downlink session.

Posted by: jmknapp Aug 21 2008, 04:29 PM

Are they using Ka band routinely for downlink? I googled it and came up with a number of references to gravitational wave studies and also studies during solar conjunction. The Cassini Significant Events page says that solar conjunction will occur Sept. 1-7. Maybe they will be using Ka-band more frequently around this time?

Right now as seen from Earth, Saturn is about 11 degrees from the Sun & will get to about 1.7 degrees separation on Sept. 4--so it doesn't actually go behind the Sun, but would have to transmit through the solar plasma with all its fluctuations, etc. A paper, http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/36798/1/01-1178.pdf, indicates that Ka-band is much better at getting through the corona:



If I read that right, maybe Ka-band would be usable right through the conjunction? The range Sept. 1-7 about covers a 3-degree separation.

Posted by: remcook Aug 22 2008, 08:45 AM

From Emily's blog:
"After that crazy flyby of Enceladus, Cassini's entering a relatively quiet period with few flybys. Saturn is approaching solar conjunction; for a one-week period beginning September 1, there will be little data returned (although if past years are any guide to the present, Cassini's radio science team will actually be using the the spacecraft's radio dish to probe the solar corona by broadcasting through it to Earth)."

Posted by: peter59 Aug 23 2008, 09:25 AM

Eclipse of Rhea by the shadow of Saturn.
August 19, 2008.

Posted by: ugordan Aug 23 2008, 01:12 PM

A colorized gif of the same sequence http://www.fileden.com/files/2007/9/14/1431389/rhea_eclipse.gif (3 MB).

Posted by: remcook Sep 4 2008, 11:46 AM

So much going on in this image...great stuff

http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=3208

Posted by: ugordan Sep 6 2008, 09:45 PM

Pandora casts its shadow onto the F ring: http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=167790

Posted by: Ken90000 Sep 6 2008, 09:48 PM

That is a great catch.

I think we are in for a wonderful equinox season with many moon casting many shadows upon many rings!

Posted by: Hungry4info Sep 8 2008, 12:51 AM

And other moons!

I'm really glad they extended the mission.

Posted by: Stu Sep 16 2008, 11:33 PM

This is just a ridiculously stunning image...

http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=3229

Posted by: Ant103 Sep 17 2008, 08:03 AM

Oh yes! Very spectacular view of Saturn sytem
Particulary the eclipse of Rhea, and the rings shadow on Mimas.

You always find great stuffs guys .

Posted by: mchan Sep 18 2008, 06:44 AM

Arrgh, the influence of Hollywood. Image reminds me of the shadow of the alien mothership moving across the Apollo 11 landing site in Independence Day.

Posted by: ugordan Oct 2 2008, 08:03 PM

A Kodak moment from Oct 1 looking down on Saturn:

http://i108.photobucket.com/albums/n15/ugordan/oct01_raw.jpg

I enhanced the cloud patterns a bit. I can't identify the shadow, judging by planet distance I get something like 19:10 UTC as the time and that matches with neither Enceladus nor Mimas.

Posted by: volcanopele Oct 2 2008, 08:30 PM

It's Tethys. And that view looks even better than the Celestia view :-O

Posted by: volcanopele Oct 2 2008, 09:15 PM

The Rev87 Looking Ahead article is now online. My Celestia rendition of that scene is included.

http://ciclops.org/view/5288/Rev_87

Posted by: peter59 Oct 3 2008, 04:03 PM

Acrux (Alpha Crucis) two components separated by 4,1 arcseconds visible by telescope:

... and observed by Cassini's NAC camera. Incredible !

Posted by: Astro0 Oct 12 2008, 07:03 AM

A nice little movie of Prometheus racing around the planet.
Beautiful view of the F-ring being distorted and a very brief glimpse of Saturn's cloudtops and the distorting effect of it's atmosphere.
 Prometheus.wmv ( 465.31K ) : 723

Posted by: Stu Oct 15 2008, 01:47 PM

Not sure if this is the right place to post this, but can't come up with anywhere better. Just thought this was very interesting...

http://www.youtube.com/watch?v=w4ghSOjlc6Y ( YouTube video )

from http://www.outsideinthemovie.com

All beyond me but some of you Imagemages will be interested, I think...

Posted by: stephenv2 Oct 15 2008, 02:35 PM

Stu, thanks for posting the link to my site. I'm very slack about posting here as I'm still working hard trying to raise enough funds to work on the film full time. Malmer and Ugordan here have generously donated some of their work to the film as have others online - I could not make the film without people like that.

I will have a new teaser online and will post it here. It has some new images I used in a 2 minute 4k demo that was output to IMAX 15/70 film and screened at Sony IMAX theater in NYC - second largest IMAX screen in the world. Unfortunately, it was a private tradeshow but that's reason I want to make this film - to get space imagery (including the Cassini/Saturn sequence which is the climax of the film) on the screen so people can experience flying through these images at the right sense of scale.

Posted by: dilo Oct 15 2008, 07:08 PM

Stephen, your work is amazing! Even though I do not fully understand the detail of your "2.75D" technique, results are quite impressive and I would like to give some aid too... let me know!

Posted by: stephenv2 Oct 15 2008, 07:20 PM

Thanks very much. The 2.75D technique is actually a recipe of various techniques to create movement with photographs that holds up at IMAX resolutions (low rez is much, much easier) and does not change the way the photograph looks. One of the key ingredients is very high resolution stills to start with and that's the best way people can help. The larger resolution images I have - especially multiple angles of the sames object, the more I can do.

Posted by: mgrodzki Oct 17 2008, 04:17 AM

good to see OUTSIDE IN… IN here.

Posted by: CAP-Team Dec 2 2008, 09:39 PM

25 and 26 july 2009 will be very exciting, on those days, the shadows of several of Saturn's satellites will cast their shadow on Titan!

1. Dione: 25 july 2009 13:21 UT
2. Tethys: 25 july 2009 13:40 UT (partial)
3. Enceladus: 25 july 2009 16:37 UT
4. Enceladus (again!): 25 july 2009 20:45 UT
5. Rhea: 26 july 11:57 UT (partial)
6. Tethys: 26 july 2009 17:21 UT

On 3 August, Dione will be in Titan's shadow (full eclipse)

Posted by: volcanopele Dec 2 2008, 11:49 PM

The only problem is that none of these eclipses are total. They are better described as transits rather than eclipses, as each of these moons are smaller than the sun from Titan's perspective.

Posted by: djellison Dec 3 2008, 12:47 AM

So they'll look more like this..?

http://www.msss.com/mars_images/moc/11_1_99_phobos/

Posted by: stevesliva Dec 3 2008, 02:58 PM

Is Cassini on the right side of things? Checked Emily's tour page and it looked like it passed Titan just before this period, and hit periapsis just afterward. So I guess that narrows my question down to... is Titan on the night side of Saturn?

Posted by: Phil Stooke Dec 3 2008, 05:57 PM

At some point we'll see ring shadows on Titan as well, not to mention on all the other moons. In fact it's going to be a complete shadow-fest around the equinox.

Phil

Posted by: CAP-Team Dec 3 2008, 08:15 PM

I never called the transits of the shadows of Saturn's satellites on Titan eclipses

When Dione is in Titan's shadow, that will be a full eclipse.

Posted by: claurel Dec 20 2008, 02:30 AM

Here's a comprehensive table of mutual events of the Saturnian satellites during the 2009 equinox:
ftp://cdsarc.u-strasbg.fr/pub/cats/J/A+A/485/293/tab4-7.dat

(I haven't checked it to see if there are any overlapping events that produce two shadows on a single satellite--seems possible, but unlikely.)

I've produced a patch for Celestia that depicts eclipse (and transit ) shadows more realistically. Due to a bug in the current Celestia release, the shadow in your attached image is much too dark. It should look more like this:



The patch accurately calculates the maximum depth of the shadow and its umbra/antumbra size. There's more about it in this thread on the Celestia forum:

http://www.shatters.net/forum/viewtopic.php?f=10&t=13323

As fun as it is to mess with this stuff on a computer, I'm really hoping that Cassini will be able to get some real images of some of these events.

--Chris

Posted by: peter59 Dec 23 2008, 08:32 AM

Nice view.
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS32/N00088053.jpg

Posted by: ugordan Dec 23 2008, 09:31 AM

Sure is. http://ciclops.org/view.php?id=3389

Posted by: volcanopele Jan 10 2009, 09:12 AM

I have to admit, this image is pretty cool:

http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS46/N00127583.jpg

The shadow of Epimetheus on the outer A ring. Acquired Jan. 8.

Posted by: dilo Jan 10 2009, 01:25 PM

Posted by: dilo May 12 2011, 03:11 PM

Sorry for using an old thread, I think today's APOD picture is worth a colorized version:

Posted by: ugordan May 12 2011, 04:29 PM

See also http://www.unmannedspaceflight.com/index.php?s=&showtopic=6702&view=findpost&p=163206 posted earlier, based on a low res Saturn crescent composite.