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Cassini image database & updates, And notifications of PDS data releases
Bjorn Jonsson
post Apr 6 2011, 01:22 AM
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The Cassini images for the period April 1 to June 30, 2010 were recently released at the PDS. This release contains *lots* of interesting satellite images, including beautiful closeups of Enceladus' plumes. There are 2 images of Mimas, 227 of Enceladus, 2 of Tethys, 181 of Dione, 13 of Rhea, 2 of Hyperion, 1114 of Titan and 170 images of Iapetus.

This is a quick and dirty false color composite of Enceladus from IR3, GRN and UV3 images obtained on May 18, 2010 at a range of 45,000. It is centered near latitude 0 and longitude 310. It has been processed to reveal compositional differences:

Attached Image


The extreme color saturation reveals that I probably should align the images more carefully but still it reveals interesting features, for exactly somewhat 'bluish' terrain in the upper left quadrant and 'blue' color near most/all fractures.

EDIT: Replaced the original image with a better version. The color channels are now more carefully aligned.
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machi
post Apr 6 2011, 08:58 AM
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Nice!

"There are 2 images of Mimas, 227 of Enceladus, 2 of Tethys, 181 of Dione, 13 of Rhea, 2 of Hyperion, 1114 of Titan and 170 images of Iapetus."

And 4 images of Janus, and some of Epimetheus and Pandora smile.gif.

Two images, second one is Janus in false colors (ir3+grn+uv3 filters), 1.5 magnified, first one is hi-res image of Dione, colorised from lower resolution images
(again ir+grn+uv filters, but notably manually corrected, so it's very artistic interpretation smile.gif ).
Image of Dione is without detailed information in index tab. So I tried excerpt some information about it.
This image covers small area in Eurotes Chasmata and big crater (at top of the image) has coordinates approx. latitude -24S, longitude 323W.
Horizontal resolution is ~14 m/pix, vertical is much lower. Highest cliffs are more than 1 km height.
Attached thumbnail(s)
Attached Image
Attached Image
 


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Bjorn Jonsson
post Apr 6 2011, 10:34 PM
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Great images, especially the one of Dione which shows a real landscape at this resolution, overall with an alien appearance but there are some features that look a bit similar to terrestrial landscapes.

And regarding Dione, I now see that there are more images of it than I thought. I found the Dione images using a database search with target='DIONE' but for these images Saturn is the target for some reason (and the viewing geometry applies to Saturn) but the target description is 'DIONE' and the target list includes Dione. Weird - and I obviously need to modify my database queries.

By the way I decided to replace the image in the starting message of this thread with a significantly improved version. I discovered that I had forgotten to rotate it so that south was originally up (north is up in the new version). Perhaps more importantly, I have now aligned the color channels much more carefully.
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Bjorn Jonsson
post Apr 6 2011, 11:39 PM
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This is getting a bit embarassing, I had to replace the image again because I discovered that the original version really *was* correctly oriented (I forgot to check a "north azimuth" orientation box in the rendering software). Everything should be correct now but if anyone notices any errors please let me know!
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volcanopele
post Apr 7 2011, 12:02 AM
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QUOTE (Bjorn Jonsson @ Apr 6 2011, 03:34 PM) *
And regarding Dione, I now see that there are more images of it than I thought. I found the Dione images using a database search with target='DIONE' but for these images Saturn is the target for some reason (and the viewing geometry applies to Saturn) but the target description is 'DIONE' and the target list includes Dione. Weird - and I obviously need to modify my database queries.

You'll see that happen when camera is not specifically targeted at the satellite. This usually occurs near closest approach when a non-ORS instrument is prime and the satellite happens to pass through the field of view, or they do a skeet-shoot sequence.


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elakdawalla
post Apr 7 2011, 04:10 AM
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QUOTE (Bjorn Jonsson @ Apr 6 2011, 02:34 PM) *
And regarding Dione, I now see that there are more images of it than I thought. I found the Dione images using a database search with target='DIONE' but for these images Saturn is the target for some reason (and the viewing geometry applies to Saturn) but the target description is 'DIONE' and the target list includes Dione. Weird - and I obviously need to modify my database queries.

I have found the TARGET_DESC field to be handy for this purpose. Most of the photos taken for optical navigation/orbit determination, which include some nice icy moon images, have TARGET_NAMEs of "SKY." An example database query:
CODE
SELECT *
FROM coiss
WHERE (coiss.TARGET_NAME='MIMAS' Or (coiss.TARGET_NAME='SKY' And coiss.TARGET_DESC='MIMAS'))

...but I didn't realize that the TARGET_NAME might be SATURN instead. Sometimes there's no substitute for browsing the whole dang data release. That's why I love the OPUS search tool at the Rings Node so much -- you can get as many as 500 thumbnails per page, color coded by filter used. They don't have the April 1 data release up yet but I expect it to be there within the next few days.


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Bjorn Jonsson
post Apr 7 2011, 10:57 AM
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I need to do some comprehensive testing to determine which query guarantees that you get every image you are looking for (assuming the metadata contains no errors) but this might work:

SELECT *
FROM coiss
WHERE coiss.TARGET_NAME='MIMAS' Or coiss.TARGET_DESC='MIMAS'

In addition it might be necessary to check whether the target_list contains the string 'MIMAS'.
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elakdawalla
post Apr 7 2011, 03:45 PM
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The challenging thing is that I usually limit my searches by TARGET_DISTANCE in order to get only images that have more than, say, 100 pixels across the disk -- but that doesn't work, sadly, if MIMAS is not the TARGET. With a little trigonometry though, at least for the inner moons, you could at least limit it by the CENTRAL_BODY_DISTANCE (no greater than Mimas' orbital radius plus whatever distance to Mimas you're looking for) to weed out spurious hits where MIMAS is in the TARGET_LIST but is only a speck.


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elakdawalla
post Apr 7 2011, 09:21 PM
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New Cassini ISS volumes COISS_2062 and COISS_2063 are now available for browsing at OPUS:

http://pds-rings.seti.org/search/results/#...meid=COISS_2062

http://pds-rings.seti.org/search/results/#...meid=COISS_2063


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Bjorn Jonsson
post Apr 13 2011, 12:40 AM
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The database updates for the April 1, 2011 data release (which covers the period from April 1, 2010 to June 30, 2010) are now available at http://www.planetary.org/explore/topics/ca...s_database.html

There are lots of interesting satellite images (especially of Enceladus and Dione) in this most recent data release.
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Bjorn Jonsson
post Nov 9 2011, 01:19 AM
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A new version of the entire ISS image database is now available here:

http://planetary.org/explore/topics/cassin...s_database.html

It includes data up to and including the most recent PDS release on October 1, 2011. The entire database was updated instead of posting smaller files containing the latest PDS releases because several recent ISS volumes had errors in the INDEX.TAB files - the subspacecraft longitude was off by 180 degrees. This has now been corrected and the database contains information from the updated and corrected INDEX.TAB files.

I strongly recommend replacing older versions of the database with this one (if you have created any queries you want to keep you should copy them from the old database to the new one before deleting the old one).
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elakdawalla
post Sep 5 2012, 05:39 PM
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The following item was published in the most recent Planetary Exploration Newsletter:
QUOTE
NEW "CASSINI ARCHIVE PAGE" AVAILABLE TO ACCESS CASSINI DATA

The Cassini mission and the Planetary Data System (PDS) are pleased to announce the availability of the "Cassini Archive Page". It has an improved interface including help pages and Users' Guide for accessing the Cassini data.

To access the Cassini data, please visit:

http://atmos.nmsu.edu/data_and_services/at...ni/Cassini.html

Or go to:

http://atmos.nmsu.edu/

and click on Cassini Archive Page
Poking around for a couple of minutes I found various useful items like this master observation schedule. Not sure what else is there.


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