There is also a set of Tethys images from about 177,000km available too.

Tethys images up: http://saturn.jpl.nasa.gov/multimedia/imag...7/N00151608.jpg

[EDIT: see below]

Nice one, charborob. The darkening in the crater walls is really pronounced in that image. Gordon's interpretation is enticing; I look forward to hearing other possibilities.

Kudos once again to the Cassini team for the spectacular views of another world. What amazing times we live in.

I made no interpretation, just said what it looks like

Merging N00151591+93+95 (green+IR2+UV2 filters respectively in place of G,R,B channels) with Saturn in background:
Click to view attachment
This is a enhanced version:
Click to view attachment

Bah! Just when I though I got my color version done before you guys. Curses!

I would like to see your version, for sure is different (at least in terms of alignment technique, which was difficult for me...)

Wonderful as always.

Yeah, Stu, the fact we get access to these images so quickly still boggles this old space hound.

What is really amazing to me is that we have this old, battered moon (on the surface) riding right next to the most active mid-sized moon Enceladus.
Location in a system does not necessarily tell the whole story?!

Craig

Janus and Epimetheus eclipses (animation)

Well since Adam beat me by a few seconds, here's a MOV file instead

Feb, 14 sequence animation:
Click to view attachment
Note the curious sudden illumination change on Epimtheus from a body on the right, perhaps from Janus itself (strange geometry, however)

Looks like "sunset" to me.

Nice catch about the change in illumination on Epimetheus. I doubt it is from Janus since that moon is clearly on the OTHER side of Epimetheus from those craters. I think we are just seeing a slight bit of rotation on Epimetheus, and the Sun is setting on the far rims of three impact craters just beyond the evening terminator.

I have to admit that I started to doubt that explanation since I suddenly thought that north might be up, so the terminator we are seeing would be the dawn one... But nope, south is up in your animation, so my explanation holds...

I do not usually throw in attachments so bare with me...

But in this Mimas image I am not convinced all the low albedo stuff is due to shadow.

Click to view attachment

It is from NAC image N00151508. Also if you look at dilo's colorized global image you can see a few darkish spots in the high phase region. Kinda like the Rhea ring impactors but more dispersed (not in a line)?

Interesting.

Craig

Wow this stuff is truly great. Honestly if it wasn't for the central peak Herschel almost looks like it formed some other way. It's just so irregular and different from other big craters, like on the moon or Callisto.
Mysteries abound!

Compare it to Rhea. Many of the larger craters on that moon are also irregular.

Mass wasting and slumping the crater walls of Herschel seem evident.

EDIT: Looking at the picture that Craig posted it seems that there is a tendency for the walls to form and slump along parallel lines going from lower left to top right.

Here are my two 'bouncy' animations of this mutual event:

Epimetheus-centric:

Click to view attachment

Janus-centric:

Click to view attachment

- Full quote deleted. Use the "add reply" button at the bottom of the page. -

Nice work !

Your animations show rotations of this monns

Grat animations, Ian! (original quality is clearly better than mine...)
Gordan, you were right!

TETHYS in (IR1, G UV3)

ir1 N00151608
g N00151607
uv3 N00151606

What we're seeing here is these two co-orbitals exchanging orbits, correct? It seems natural to think that the switching of orbits would need to cause temporary redirections of the moons from their normal elliptical orbits, and therefore the observed rotations and exposure of hidden surfaces to the sun.

I'm not exactly sure where they are in the process of exchanging orbits, but I think the relative movement we see here is mainly the changing perspective of Cassini as it rushes by.

This is not the orbital switch. There are several factors - the moving spacecraft, the moons moving relative to the sun and to each other.

Phil

But changing the observer's perspective couldn't account for the change in illumination of the subject. We must be seeing physical rotation of the moons themselves relative to the sun.

"in this Mimas image I am not convinced all the low albedo stuff is due to shadow."

These patches don't look unusually dark in images with more overhead lighting, which you can see further up the thread. - but there are real dark spots in places further east.

Phil

Yes, exactly. These movies are taken over a non-insignificant fraction of the day for these moons. But it doesn't have to do with any interaction between the two moons.

Okay, I get it. Thanks. So the rotation we're seeing is just the normal rotation of these moons. "Sunset", like Gordon said about 10 posts ago.

(I should know better than to post before doing my homework. The switching of orbits happened on January 21, more than three weeks ago.)

I finish colorize MIMAS. This dark areas are more visible.

ir2 N00151593
BL1 N00151591 (like chanel G)
uv2 N00151595

Adam, it says "Limax 7" in the corner of your images. What does that mean?

It's my nick in polish forums: astro4u and astro-forum.org (the largest polish astro forums)
but also I use this nick in other groups: comet-ml

Final adjusted color composite RGB [IR1, GRN, UV3], with enhancement in the overexposed region:

Click to view attachment

The ridge at the limb to the upper right of Odysseus is likely a remnant of another large impact basin.

Full res here: http://www.flickr.com/photos/31678681@N07/4361319512/

My mosaic is not of good quality, I hope that someone will do it better, but the view is impressive.
Click to view attachment

It's underexposed.

Nice 'little' storm:
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=213757

Too contrast-stretched would be a better description.

And my Mimas mosaic from 4 images:

N00151557.jpg
N00151553.jpg
N00151577.jpg
N00151578.jpg

Color Titan image from 16 Feb. 2010

I use images:

RED and CL2 filters: http://saturn.jpl.nasa.gov/multimedia/imag...7/N00151632.jpg
CL1 and GRN filters: http://saturn.jpl.nasa.gov/multimedia/imag...7/N00151634.jpg
BL1 and CL2 filters: http://saturn.jpl.nasa.gov/multimedia/imag...7/N00151633.jpg
CL1 and CB3 filters: http://saturn.jpl.nasa.gov/multimedia/imag...7/N00151636.jpg


FINAL image:

Nice to see this moderately high resolution mosaic. Maybe advantageous for mapping.

I had already checked your site for a map update

I already tried updating my copy of Steve's map Steve, what size did you use for Mimas? Did you assume a spherical Mimas? I converted my mosaic to a simple cylindrical map and I can't get things to line up.

CAP-Team - my first step in updating the map is using a more full disk low-phase image as can be seen here:

Click to view attachment

VP - I'm using these three triaxial dimensions: 414.8 394.4 381.4. Good question about the fit as Mimas is a great test of our handling of triaxial ellipsoids. Here is a look at the degree of fit (and size relative to the limb) with the image I'm using:

Click to view attachment

How nice to have Saturn backlighting & highlighting the dark limb, right where this is needed

Steve

Well, the issue that I have is that my Herschel comes out looking oblong in the north-south direction, which I think it should..., but it pushes some of the craters north and south of Herschel closer to the poles than what is shown in the map on your website.

Sounds like the dreaded Peters Projection! Seriously, is it a map projection mismatch?

Phil

Perhaps VP is working with a planetographic map as I think that corresponds with an oblong appearance for Herschel. The official maps on the CICLOPS site also appear to be planetographic. Conversely I am working with planetocentric coordinates (still on the triaxial ellipsoid), where Hershel should probably look more round.

It appears possible to convert between planetocentric and planetographic. One way (at least for the latitude part) might be the reverse of what is discussed below:

https://isis.astrogeology.usgs.gov/IsisSupp...hp?topic=1550.0

Here BTW is a map using three images from the new flyby.

Click to view attachment

Steve

P.S. I recall running into the Peters projection on another project, thankfully not this one!

Looks great even though the contrast stretch is a bit extreme for my taste (completely black shadows in craters etc.). Is the automatic contrast stretch applied to the source images one of the reasons for this?

Bjorn - yes it's true this looks quite a bit more contrasty and darker compared with say my Enceladus map. For Mimas many of the first images on the map were at higher phase angles. That coupled with such a battered surface tended to give a preponderance of shadowed craters. This kind of became the norm for contrast when newer images are added. New images at low phase thus have to be contrast stretched quite a bit to look consistent. Nonetheless it appears to be a good suggestion and I will try to soften the shadows (and avoid losing details) with some of the imagery.

Here's a slightly less contrasty 4K version:

Click to view attachment

Steve

Steve, what software you use to making maps? I searched Google and nothing..

Adam - I'm using IDL. Using this software I wrote various procedures that help me navigate images, handle the map projections, and do the mapping.

Steve

Iapetus color image (19 Feb. 2010)

N00151720.jpg ®
N00151716.jpg (G)
N00151719.jpg (

Nice! Here's my version Used all the images, stacked to attempt to reduce JPEG artifacts, enlarged 200%.