I'm not sure about the margin for turns while mosaicing but for a 180 degree slew the times are

Roll about X-axis ~30.5 minutes
Roll about Y-axis ~25.8 minutes
Roll about Z-axis ~16.4 minutes

using high power for the reaction wheels
and

Roll about X-axis ~58 minutes
Roll about Y-axis ~42 minutes
Roll about Z-axis ~38 minutes

using low power for the reaction wheels

and a 180 degree RCS turn is about 11 minutes

The settling time after a turn is nominally about 60 seconds I think.

Wow, I assumed the reaction wheel figures were high but these are quite substantial indeed. Is the time difference primarily due to different mass distribution along each axis? I can't seem to dig up a schematic showing the orientation of principal axes, but this would suggest the Z axis running along the length of the s/c, parallel with HGA boresight and the X axis being the most inert of them, orthogonal to the plane in which HGA boresight and magnetometer boom lie?

How do these figures change with propellant depletion (if at all)? Optimizing slew maneuvers is no doubt one of the (many) factors in increasing useful observation times...

I really like the new layout, much more bandwidth friendly and the color-coded filters are also a nice touch. How did you find all those Photojournal releases derived from Dione sequences - manually by dates?

One thing regarding the full size PNGs. They are 16 bit, but are very dark, perhaps a uniform scaling factor could be applied to all images to maximize DN in the PNGs. IIRC Bjorn's IMG2PNG does implement this feature. This would ideally be the highest scaling factor that keeps the brightest albedo object in the Saturnian system (i.e. Enceladus) from being overexposed, of course taking into account its weird zero-phase geometric albedo of 1.375. I don't know what scaling factor you currently use, but if low enough it might in fact reduce s/n ratio if the 12bit images are fit into 8 bit values.

Thanks. For the Photojournal images, I just searched on Dione, and then I matched the dates and, when date was ambiguous (or, in one case, incorrect), I matched the phase angles and distances. A bit tedious but that's one thing I've been very curious about -- just how many of the "good" images have been released to the public in one way or another? It's not a bad proportion, it turns out, but it's not all of them by any means, and there is a LOT that can be done that hasn't yet been done with color data.

The 16-bit images do have a variety of brightnesses, but I did use IMG2PNG with the "-r" switch and all the Cassini calibration data to calibrate them as I did the format conversion. Clear and green filter images do seem to be pretty reasonable in their brightness, UV ones are pretty dark -- which is more or less what I expect, actually. Remember that Dione is somewhat dark as icy satellites go. Maybe Bjorn can comment on whether the full-size images look like they are supposed to, especially in the UV. I did get errors on every WAC image upon conversion though, so I'm not sure that those are properly calibrated. Of the 900 or so NAC images, IMG2PNG reported errors during the calibration step for about 20 of them.

On the next go-round I'll do Enceladus and we can see how different those look.

--Emily

I was intrigued by some fairly big brightness differences between different filters in Emily's page. For example the UV images turn out much darker than when I throw them through my software. I decided to do a comparison of narrow angle frames N1507738546_2 (RED,CL2), N1507738663_2 (CL1,GRN) and N1507738491_2 (BL1,CL2). Below are simple RGB composites, modified only to resize and register the three filters:


The left image uses IMG2PNG converted data, the right one is my calibration result.

I didn't touch the channel balance in the left case, there are a couple of notes about my results:
I do all the calibration steps except dark current removal. In practice this doesn't amount to anything than a slightly brighter background signal in the longer exposed images (blue and especially UV in NAC and violet in WAC case) and is in no way capable of such a drastic difference. If you really kick up the saturation in my image, you'll see the bluish hue likely due to dark current.
Other than that, I use the official calibration "fudge factors" found on COISS_0011 with a slight modification for RED/CL2 filters. Early on I realized the red channel turned out consistently too bright with those factors so I worked out it needed to be multplied by 0.949 to bring it in line with other filters. The official calibration factors might indeed be off since they're quite old as a contact from PDS emailed me, in fact the whole calibration procedure was greatly improved since then. I don't have too much faith in other infrared filter factors either. Such factors weren't even derived for WAC and are missing from the calibration volume.

The color of Dione's surface in the left case suggests to me it shows the total radiance as seen by the instrument. It reminds me of my VIMS experiments without dividing by solar spectrum as sunlight is actually yellowish.
In my calibration procedure the filter transmissivities are divided by integrated solar spectrum and produce reflectance (I hope it's the right term) instead, the intrinsic color of the moon if you will. This is consistent in that it produces gray Mimas, Enceladus and gray non-stained hemispheres of Dione and Tethys. In essence the color they'd appear if shined upon by a big, white light lamp.

I like your page elakdawalla

Reminds me of a similiar thing I did for Themis. Apologies for the file share download, but it's all I have at the moment.

MouseOnMars

It's starting to appear, the ISS volumes COISS_2026 and COISS_2027 are up, but not searchable yet. They can be accessed directly:
http://pdsimg.jpl.nasa.gov/data/cassini/ca...ter/coiss_2026/
http://pdsimg.jpl.nasa.gov/data/cassini/ca...ter/coiss_2027/

I've done a preliminary browse of the thumbnails to see if anything interesting's up. This is still the time period when Cassini was spending a lot of time on the nightside, seeing unlit rings. The real good Saturn stuff should be appearing in the Jan 1, 2008 release.

In the meantime, here are a few takeouts:

Hyperion in natural color, 2x magnified.


Iapetus in natural and IR3/GRN/UV3 color, 2x magnified. November 27, 2006.


Couple of Saturn north pole shots. A moon shadow (probably Mimas) visible near the terminator in the left image.

Titan and a lovely shot with Saturn's hazy limb showing through the translucent, unlit rings:

I've been waiting for this!! Thanks for the notice, Gordan.

Bjorn, I'm ready to make the database update whenever you can put the tables together.

--Emily

This also means that some of my favorite SAR swaths, from T19, T20 (HiSAR over Tortola Facula), and T21 will also be released.

The information from this ISS release is now ready for getting added to the Access database described in this thread (see this message). The database includes all of the information from the index.tab files and makes the images much easier to work with.

As before, Emily has hosted them on the same server as the database:

http://filicio.us/tpss3/files/31020/cassin...es_index_26.zip
http://filicio.us/tpss3/files/31032/cassin...es_index_27.zip

These are Excel files that must be added to the Access database as described here.

The ISS volumes Coiss_2026 and Coiss_2027 are now available from
PDS Planetary Rings Node in zipped form (convenient for downloading).

Coiss_2026 and Coiss_2027 in zipped form

There is an early 'Christmas present' at the PDS: The January 1, 2008 data release (ISS and VIMS) is already there. I have managed to take a quick look at all of the ISS images and post a summary at http://www.mmedia.is/bjj/misc/css_stuff/im...s_overview.html . This also includes all of the earlier ISS data volumes.

With the exception of Titan, there are very few interesting satellite images this time, Cassini's orbit was highly inclined. The most interesting ones are probably the ones of Hyperion in coiss_2029\data\1550261798_1550410364 (mentioned by Emily in this thread).

There is heavy emphasis on the rings with lots of various movies including F ring movies, spoke movies etc. plus lots of multispectral coverage showing both the lit side and the unlit side. There are also many interesting images of Saturn, mainly WAC images. These include great images of the south pole obtained at high inclination. There are several images there that I'm going to process when I have the time (probably immediately after Christmas).

Updates to the Cassini image database (see this thread for further details) are available at the following URLs for volumes coiss_2028, coiss_2029 and coiss_2030 respectively:

http://planetary.s3.amazonaws.com/data/cas...ta/index_28.zip
http://planetary.s3.amazonaws.com/data/cas...ta/index_29.zip
http://planetary.s3.amazonaws.com/data/cas...ta/index_30.zip

Lot of good stuff in this PDS release. Your summary page is very helpful, particularly before the new data becomes searchable on the PDS.
Here's a quick Saturn composite, just part of a sequence of color ring plane crossing Ian Regan animated back in the day:

"....There is heavy emphasis on the rings with lots of various movies including F ring movies, spoke movies etc. plus lots of multispectral coverage ..."

My recollection is that the Voyagers got surprisingly little multispectral coverage of the rings. Imaging sequences concentrated on things like phase and inclination angle, radial structure mapping, etc, followed by the big "spoke movie" from Voyager 2 after the Voyager 1 spoke discovery.

I think I recall that one mision (maybe Voyager 1), got only orange/blue or some such 2-filter moderately high rez color coverage of the rings. I suspect there was no expectation that the rings would have widespread color variation and only minimal effort to check for radial color variations was worth the data-bandwidth.

There is definitely a large body of high phase multispectral ring data from Voyager. I am not sure about data taken on approach.

I've made progress on my massive project to make the better images of the icy satellites more accessible to people. I'm not quite done with it -- I still need to sort out and format pages for Phoebe and the rocks, and have a bunch of introductory and explanatory text to write -- but for those of you who don't need any hand-holding to enjoy PNGified versions of every decent-sized icy satellite image in the PDS, here's the work in progress: Selected Data from Cassini's Cameras. I decided to post it now even though it's not done because I think MESSENGER may keep me too busy this week for me to do any more work on it for a bit.

--Emily

Folks, just a heads up that 3 new ISS DVDs are now available at the PDS, covering a data collection period period of April 1 - June 30, 2007:

http://pdsimg.jpl.nasa.gov/data/cassini/ca...iter/coiss_2031
http://pdsimg.jpl.nasa.gov/data/cassini/ca...iter/coiss_2032
http://pdsimg.jpl.nasa.gov/data/cassini/ca...iter/coiss_2033

Just glancing through the index tables, apart from the usual assortment of Titan flyby imagery, Saturn and rings, there are some nice higher resolution multispectral observations of Dione, Tethys, Rhea and Atlas (highest res imagery throughout the mission) and also lower resolution stuff on Mimas and Iapetus (Cassini's first good look at the trailing side), Enceladus low phase observations, couple of mutuals, etc.

Also, new VIMS data is here:
http://pdsimg.jpl.nasa.gov/data/cassini/ca...er/covims_0019/

As usual, Bjorn has created updates to the massive Cassini Image database for this latest release. For those of you who haven't seen it before, Bjorn made a Microsoft Access database containing all the metadata for all the images released by Cassini ISS to the Planetary Data System. This database is great because you can construct really quite complex queries and have it spit out lists of images that you might be interested in -- for instance, you could, if you wanted to, find all images that contain both Saturn and Titan that were taken through a RED filter, or find all images of Atlas with resolutions higher than 5 km/pixel, and so on. I use it to produce lists of files that I can then run wget on to automatically download only the images I'm interested in.

I have now created a page on the Society's website that links to the original database and all the updates. Enjoy! And don't forget to check out the pages I made that show all reasonably good images of Saturn's moons (excepting Titan) -- I haven't updated these pages yet with the April 1 release but I'll begin to work on that now that Bjorn's updated the database.

--Emily

It's amazing that Emily has put these pages together for all the main icy satellites. Nice that the images appear to be more directly usable without the need for 16-bit to 8-bit conversion (or at least my viewers are doing this more easily now). I also note the sub-spacecraft lat/lon that are useful in mapping. I wonder how these were obtained since when I browse the headers on the PDS web pages I usually just see the image center point lat/lon. I see these are listed in the more complete list of header definitions on Emily's page. Just FYI, I also like to use the sub solar lat/lon info for mapping. Kudos to Bjorn as well.

Steve

Everything in the database is taken from the index.tab files - there is one index.tab file for each ISS volume. These files contain a lot more data than the LBL files (or the headers in the IMG files). The database includes everything from the index.tab files.

Here's the best icy moons and rocks stuff from the latest release. --Emily

http://www.planetary.org/data/cassini/u08q2icy/
http://www.planetary.org/data/cassini/u08q2rocks/

The ISS images for the July-September 2007 period have hit the PDS even though July 1 is several days away. I haven't had time to look at much yet but know there's a lot of interesting stuff there. The highlights I remember are:

* The only targeted Iapetus flyby
* A 5000 km nontargeted Rhea flyby
* A very nice flyby of Dione (~40,000 km IIRC)
* Lots of nice Tethys images
* Several Titan flybys

Ooh, nice catch, Bjorn. I was checking it myself earlier today and no luck. This is as fresh as it gets

Iapetus!!!! I can't believe it's been long enough since that flyby that the data is on the PDS already. I can't wait to see what you guys produce from that data set.

I'm looking forward to downloading stuff -- but probably can't get to it until this weekend. Bjorn, I'm ready for the database update whenever you get around to it.

--Emily

A taste of Iapetus data, from the Saturn system PR sequence before C/A. RGB color:

I forgot which star that was to the above right of Iapetus and also apparently another one off the sunlit crescent.

EDIT: Quick regional RGB color on the outbound part and one of the parting shots on the right at 2x:


The dark stuff truly is remarkably gray on the trailing hemisphere. I'm now wondering whether my plan for redoing the big outbound mosaic in approx. natural color is worth the trouble just to get essentially b/w imagery in the end. There are still odd false color high-res mosaics here and there, though, that weren't released officially.

Ooh! An amuse bouche if I ever tasted one

--Emily

In French, the word is "amuse-gueule". I agree with you: very tasty.

Another tidbit from the release: an approx. natural color ring scan of the left ansa, consisting of 5 NAC RGB segments. This was taken a couple of days (Sep 7 IIRC) before the Iapetus encounter and shows a similar vantage point. There's also the right ansa data at the PDS, but it doesn't show as much interesting stuff (Mimas, Pan and Prometheus).

I am wondering how can I decode PDS ".img" file on my mac. I have OS 10.5.3 and before, on my old pc, I have found a Gimp plugin to read .IMG files. Gimp 2.4 run on OS 10.5, but, the plugin is not compiled and I don't know how to do . This is for Gimp, but, I imagine that there are other solution .
Doug : you are on a mac, how do you do?

I use a PC

Seriously - I do - img2png on my desktop PC machine.

My MacBookPro is my 'life' machine (Email, calender, presentations, photos etc), my PC desktop is my 'power' machines (storage, PTGui, cold hard data, 3d rendering, Photoshop)

Doug

And now when I am at last ready to start large scale downloading Murphy's law strikes and I cannot access the PDS imaging node. I guess I'm not the only one...

Blerg. I can't access it either.

--Emily

I find that the PDS site is unavailable all too often. I'm not sure if it's a maintenance thing, but weekends usually seem to be iffy. Very annoying.

I love this shot! Mimas is posed perfectly, and Pan and Prometheus... just amazing.

I just exchanged emails with some folks at the PDS. They know about the problem, has something to do with an expired something-or-other on a server so access isn't currently permitted; they hoped the problem would be resolved some time today.

--Emily

Looks like they need a mission extension as well.

took advantage last week and downloaded and calibrated everything. i should have the geometry
corrected next week sometime, while i tour china....
wow stuff!
paul

You're just trying to make us jealous. Admit it.

Problem resolved, site is available. Vol. Coiss_2034 - Coiss_2037 released.

The ISS volumes Coiss_2034, Coiss_2035, Coiss_2036 and Coiss_2037 are now available from PDS Planetary Rings Node in tar.gz form (convenient for downloading, even with a 4:1 compression ratio).

COISS_2034.tar.gz - 1208 MB
COISS_2035.tar.gz - 1026 MB
COISS_2036.tar.gz - 1117 MB
COISS_2037.tar.gz - 167 MB

Volumes Coiss_2034, Coiss_2035, Coiss_2036 and Coiss_2037 in tar.gz format

Still waiting for all the RADAR swaths to return.

Björn sent me these last week and I finally posted them: the Excel updates for the latest four volumes for his Access database to all Cassini images. Download from here.
--Emily

After living with the browse pages I'd made for the Cassini PDS images, I decided I didn't like them, so I am trying out a new design, more like the one I did for the RAC pages. Please check out my new index to all reasonably good Cassini images of Enceladus and let me know what you think; after a little input I'll go ahead and do these for the rest of the moons. (An example of my old design is here.)

To whet your appetite, here's some plumes from rev 50.
Click to view attachment

--Emily

That looks brilliant Emily, a really useful resource I think. I know for a fact I haven't got the imaging skills or tech savvy to make any real practical use of it, but others here - and elsewhere - will, and they'll appreciate all your hard work and effort I'm sure. It is a lot neater and more easily navigable than v1.0. Great seeing all the plumes images in one place, really brings home just how fascinating and important a moon Enceladus is.

Agreed - and nine days until the next sub-50km flyby, featuring amongst other things, some close-ups of the plume vents

Hmm. It's kind of distressing to hear you say that -- this is intended to serve the same function as the raw images pages for Cassini, or the Phoenix mission, or whatever, except that it is supposed to provide access to much higher-quality, non-JPEGgy, non-contrast-stretched data that's archived in a way that makes it tough for amateurs to access. I'm trying to solve that access problem and make these much better data available to the public. You can do all the same stuff with these images that you can do with the raw Cassini images, you just aren't hobbled by the limitations of the raw data site. Clearly I need to do something to make this more accessible to you -- what do I need to do?

--Emily

Sorry Emily, that came out wrong! I meant use it in the same way that our experts here - ugordan, james, etc - will use it, i.e. making elaborate mosaics and finely colour- and level-balanced images. I don't have the software, experience (or patience!) to create the masterpieces they do. But I will definitely be using it to make simpler RGB composites and to pull details out of images of plumes and surface features, for use in my Outreach talks, and have already started on a couple of images today for use in my astro soc meeting on Monday night...

I'm resurrecting this old thread to announce a new version of the database discussed earlier in the thread. All of the errors I mentioned there have been fixed and the database includes information for all of the ISS images released to the PDS so far (almost 200,000 images).

As earlier Emily has provided hosting for this big file (it's about 85 MB zipped). Further information is available here:
http://planetary.org/explore/topics/cassin...s_database.html

I just noticed that the January 1, 2008 ISS PDS release is already there. What's more, there is now a compressed (GZ) file available for each volume. This is a very welcome addition - it reduces the amount of data to download and more importantly, download errors now manifest themselves as error messages during decompression. This is very important as I have discovered a few cases where files got corrupt during downloading without any error messages appearing during the download. Because of this I may even gradually redownload everything I have previously downloaded, this time as GZ files.

I haven't downloaded anything yet but now I know this weekend is going to be a 'download weekend' .

*Glub glub glub*

That's the sound of Emily drowning in data. I haven't even wrapped my mind around the last PDS release yet! Not that I'm complaining.

--Emily