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Rev 138 - Sep 13-Oct 4, 2010 - Titan T72
Hungry4info
post Sep 15 2010, 06:29 PM
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A nice shot of Janus.
http://saturn.jpl.nasa.gov/multimedia/imag...3/N00163151.jpg

Some more (severe) data drop outs v_v.
http://saturn.jpl.nasa.gov/multimedia/imag...2/N00163150.jpg


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elakdawalla
post Sep 15 2010, 06:37 PM
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Unlike MER, Cassini doesn't release raw images if their first transmission had data gaps; JPL holds back release of any Cassini images with data dropouts, in the hopes that Cassini will be able to retransmit the data. Once in a while, Cassini empties its data recorders (usually but not always in preparation for a targeted flyby) and then JPL has to give up on getting better versions of the images, with the result that you'll suddenly see a big batch of images with data dropouts and old dates hit the raw images website.


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Frank Crary
post Sep 16 2010, 06:29 PM
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Cassini empties the recorders every few days, and almost never retransmits data. Retransmission is a planned, automatically-play-back-twice practice that's reserved for Titan and icy satellite encounters. You're probably seeing the difference between data the DSN sends to JPL immediately, and the "bested" data. There is some level of error correcting that the DSN can do, to recover packets corrupted in transmission, which they can't do on the fly. That is usually available a few days after the bits hit the ground. The really ratty data is probably from downlinks where the conditions were so bad that no amount of reprocessing and error correction can help.
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JRA
post Sep 18 2010, 03:37 AM
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QUOTE (ugordan @ Sep 4 2010, 09:16 AM) *
Dione mosaic, 3 clear frames from around 78 000 km. North should be somewhere around 10 o'clock.


I really like this image of Dione. It would make for a great desktop background. But I would just like to ask, is there be a version with less .jpg compression?
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elakdawalla
post Sep 18 2010, 04:22 AM
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Those ring shadows are moving south pretty fast.
Attached thumbnail(s)
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ugordan
post Sep 18 2010, 10:44 AM
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QUOTE (JRA @ Sep 18 2010, 05:37 AM) *
But I would just like to ask, is there be a version with less .jpg compression?

Those artifacts are in the raw jpegs, not caused by output compression setting so no.


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JRA
post Sep 18 2010, 11:59 AM
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QUOTE (ugordan @ Sep 18 2010, 02:44 AM) *
Those artifacts are in the raw jpegs, not caused by output compression setting so no.


I was afraid that might be the case, but I thought I'd ask. Thanks for the reply.
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Phil Stooke
post Sep 18 2010, 01:00 PM
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But wait six months and you'll have the 'real' raws with no compression!

Phil


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ugordan
post Sep 18 2010, 01:41 PM
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For this particular observation that works out to 10 months.


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JohnVV
post Sep 18 2010, 08:48 PM
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for the image "dione_20100903.jpg"
"But I would just like to ask, is there be a version with less .jpg compression?"

they are not all that bad , i have seen far,far worse

in some of the celestia add on's ( some so bad i want to reject them )

but if you want here is a copy that i removed most from (as always, there is always a trade off with sharpness so...)

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Floyd
post Oct 9 2010, 04:15 PM
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How many moons can you see in this image--four are easy and there may be 2-3 others?
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jasedm
post Oct 10 2010, 08:05 AM
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I'm reckoning (without checking any simulators) that there are 6, and anticlockwise from bottom left they are:

Epimetheus, Daphnis, Pan, Janus, Enceladus and Atlas

Couldn't spy any more.....
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ugordan
post Oct 22 2010, 05:44 PM
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Here's a rough guess on how that scene might have looked like:
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