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Posted by: Ian R Mar 5 2007, 04:04 PM

I started working on the following mosaic on the 22nd of February, and just over 10 days later, it is finally completed. At times it was an extremely frustrating process indeed; however, as each tile fitted together and more of the finished composite was revealed, I grew ever more excited.

Now it is with a big sigh of relief that I can finally reveal Saturn as she presented herself to Cassini on the evening of the 20th of February, 2007:

I dedicate this image to all the great folks here on UMSF who have greatly enriched my enjoyment of space exploration.

Enjoy!

Ian.

Posted by: Ian R Mar 5 2007, 04:11 PM

The mosaic includes all of the moons interior to Dione, apart from Daphnis and Epimetheus. Here are some excerpts from the composite with each moon labelled:

The same view courtesy of Mark Showalter's Saturn Viewer 2.5:

Posted by: ugordan Mar 5 2007, 04:14 PM

Posted by: Ian R Mar 5 2007, 04:15 PM

Finally, here's a sample of the full-size image:

Due to technical reasons, I can only post the mosaic at 50% its original size (in other words, my computer is too crap to handle the full-res image in its entirety!).

Ian.

Posted by: Stu Mar 5 2007, 04:16 PM

Oh... my... word.....

If you don't mind me showing it to them, this will knock em off their chairs at my astronomy society meeting tonight... and at EVERY talk I do from now on!

Good job Ian. Good job.

Posted by: Tesheiner Mar 5 2007, 05:26 PM

(This might be my first post on a Saturn thread.)

Hats off, Ian!

Posted by: djellison Mar 5 2007, 06:01 PM

****

That's sweet

Posted by: lyford Mar 5 2007, 06:34 PM

Now I need an Outer Planets Swear Jar.

Posted by: As old as Voyager Mar 5 2007, 07:59 PM

Thanks for all your hard work Ian. That mosaic is incerdible!

Posted by: Ian R Mar 5 2007, 10:39 PM

Thanks everyone for the kind words - the cheques are in the post as I type!

Stu, you are more than welcome to use ANY of my pictures in ANY of your talks. Good luck, and I hope it goes well tonight (I just hope this reply isn't too late).

Ian.

Posted by: Stu Mar 5 2007, 11:08 PM

Ian, there were 33 people at my meeting tonight and I reckon I heard 32 gasps when that image came on the screen... and it was a BIG screen! To put it in context I showed it after showing some images I took of the Saturn occultation from last week, and immediately after the recent official Cassini pix... when yours flashed up several people swore, I'm not joking!

I have four talks lined up for the British "National Science and Engineering Week" mid-March, roughly 300 people, so they'll all enjoy your pic too.

Well done again.

Posted by: edstrick Mar 6 2007, 07:58 AM

drool.

Posted by: Ant103 Mar 8 2007, 06:17 PM

Very good job. It's a beautiful Saturn picture!
You are the best in Cassini image processing so far I know

Many thanks!

Posted by: elakdawalla Mar 9 2007, 05:34 PM

I http://www.planetary.org/blog/article/00000901/ and counted up a total of seven complete multispectral mosaics on the planet since the 19th. For those of you who want to take up Ian's work now that he's been driven mad by doing two of these, you could assemble the mosaics from: February 5 (unlit side, ring opening angle 30ish degrees); February 18 (lit side, ring opening angle in the high 50s, Saturn at roughly half phase), Feburary 19 (lit side, ring opening angle in the high 50s, Saturn at mostly full phase), or February 27-28 (unlit side, ring opening angle in the high 50s, Saturn in a crescent phase).

Some of the images are unfortunately marred by some stripy noisy data dropouts (like http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=104465). I've heard that this is due to a bad sumbodule (one of 128) on one of the SSRs. It must have been hit by some extra-energetic cosmic ray and is corrupted. They're working on a flight software update that will automatically skip over this submodule, but it won't be uplinked for a couple of months, so we'll continue to see those from time to time.

--Emily

Posted by: Ian R Dec 5 2007, 11:52 PM

I've reprocessed the colours in this mosaic in light of the official Photojournal http://photojournal.jpl.nasa.gov/catalog/PIA08367, which only covers the bottom-left corner of the entire view:

Unfortunately, it seems as if the centre tile is over-exposed to the point of saturation, although I haven't yet looked at the PDS release to see if that is indeed the case.

Ian.

Posted by: ugordan Dec 6 2007, 09:56 AM

This data is not yet available on the PDS (scheduled for January 2008), but unfortunately all evidence points out to the actual raw data being overexposed as well. How they couldn't figure out a correct exposure for a low phase view of a well characterized target puzzles me (all the more because gaseous objects don't tend to display great brightness variations vs. phase angle). The same issue was present in the very first huge Saturn mosaic, it was only the second big one which got the exposures right (http://ciclops.org/view.php?id=483).

It's a shame because this particular view shows a vantage point pretty similar to what can be observed from Earth and it would make for a nice comparison to those cool Hubble views.

Posted by: tedstryk Dec 6 2007, 12:26 PM

Great work with the data available! It is surprising that it is so overexposed....For the central disk, it is hard to think of a reason. I have my fingers crossed that it is another quirk of the "raws," and that the overexposure is not real.

Posted by: ugordan Dec 6 2007, 12:52 PM

The fact CICLOPS only released the bottom portion of the mosaic as Ian said suggests otherwise, unfortunately. It should be noted that a few filters are not overexposed, but IIRC they are in the infrared region.

Posted by: ugordan Dec 23 2007, 11:02 PM

Here's a rather quick mosaicking attempt at the calibrated version of the mosaic (just hit PDS) (2 megabytes full res view): http://www.fileden.com/files/2007/9/14/1431389/overexposed_saturn.jpg

It's poorly registered, but it shows the original data is indeed overexposed as I suspected.