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Iapetus Far-Encounter between March 25 and April 18 2006
TritonAntares
post Mar 14 2006, 01:04 PM
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First of all, again the two existing encounter animations:
Animation 1
Animation 2

Nearest approach:

Resolution about 3,6 km/pxl.

And some pre-info about upcoming encounters:
2006 Mar 25 to Apr 18: Apr 11 - 602.412 km; 14-3.6 km/pxl; medium to high phase, southern hemisphere as crescent
2006 Jun 17 to 27: Jun 23 - 1.343.000 km; 14-8.1 km/pxl; medium to low phase, sub-Saturn hemisphere
2006 Sep 08 to 09: Sep 02 - 1.816.000 km; ~20 km/pxl; zero phase (3 to 0.05 deg), sub-Saturn
2006 Nov 26: 1.997.000 km; 12 km/pxl; very low phase, sub-Saturn
2007 Feb 12 to 15: Feb 14 - 2.249.000 km; ~14 km/pxl; sub-Saturn; very low phase and eclipse
2007 Apr 14: 2.256.000 km
2007 Jun 22: 1.817.000 km; ~14 km/pxl; med. phase, trailing side
2007 Sep 03 to 09: 8.6-0.7 km/pxl; very high phase, western Cassini Regio
2007 Sep 10: 480-10-540 m/pxl; targeted flyby, trailing side
2007 Sep 11 to 17: 0.7-7.1 km/pxl; low phase (~33 deg) trailing side
2007 Sep 27: 15 km/pxl, low phase sub-Saturn+trailing side
2007 Nov 26: 1.371.000 km; 8.2 km/pxl; very high phase, north pole, possibly graylight
2008 Feb 13: 2.045.000 km; 14 km/pxl; high phase, north pole, possibly graylight

Days around Sep 10 belong to the targeted fly-by in about 1000 km distance,
others will only be some OPNAVs.

Bye.
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TritonAntares
post Mar 17 2006, 10:28 AM
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QUOTE (TritonAntares @ Mar 14 2006, 02:04 PM) *
First of all, again the two existing encounter animations:
Animation 1
Animation 2
...

I've forgotten a third one:
Animation 3

Not so nice concerning the drawn textures, but showing dates and distance data.

I've tried to create an additional one with 'Celestia', but I came in trouble with zooming in from Cassini to Iapetus. sad.gif mad.gif
Also I did a mistake in using Steve Albers latest map. It's centered on 0, not on 180 as 'Celestia' wants.
So I was quite surprised in seeing the equatorial ridge with its white mountains in prime focus at end of this month... huh.gif blink.gif
Is anyone able to convert it into the 180 seight? 1024 x 512 pixels would be sufficient.

Alternativly is this map from December:

Attached Image

'Terra incognita' is shown in black...
but not so nice as Steves' map.

Thx and Bye.
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angel1801
post Mar 17 2006, 01:16 PM
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QUOTE (TritonAntares @ Mar 17 2006, 07:58 PM) *
I've forgotten a third one:
Animation 3

Not so nice concerning the drawn textures, but showing dates and distance data.

I've tried to create an additional one with 'Celestia', but I came in trouble with zooming in from Cassini to Iapetus. sad.gif mad.gif
Also I did a mistake in using Steve Albers latest map. It's centered on 0, not on 180 as 'Celestia' wants.
So I was quite surprised in seeing the equatorial ridge with its white mountains in prime focus at end of this month... huh.gif blink.gif
Is anyone able to convert it into the 180 seight? 1024 x 512 pixels would be sufficient.

Alternativly is this map from December:

Attached Image

'Terra incognita' is shown in black...
but not so nice as Steves' map.

Thx and Bye.


I (out of interest as "Celestia" is referenced here alot), decided to download it. I was not happy with the textures they used for Saturn's moons, so I decided to use Steve Albers maps. And I can get them to work.

Here's how. Copy his maps to the "textures --> hires" folder and remove anything after the body's name on the file name. ie "Tethys_www_cyl_rgb" to just "Tethys". Do the same for all the other "Hires" textures. When you load Celestia, choose "Hires" mode and select the maps you have just loaded.

And to solve the problem with the maps being centered at 180W reather than 0W, just do a mental calculation to adjust for the problem.

ie To have the "The Great White Splat" (12S, 111W) centered on a Rhea Map, select -12 for latitide and 69 for longitude.

69 = -111 (=111W longitude) + 180

Another example "Tirawa" centered Rhea,

Latitude = 34.8 (34.8N)
Longitude = 28 (-152 + 180) [-152 = 152W]

Again using Rhea, "Evil Twin" (10N, 180W) would be imput as +10 latitude and 0 longitude.

I have collected a wonderful collection of Saturn's moons and and a variety of views. I have got polar views (centered on both north and south poles) for all of Saturn's moons that I have a good map for (provided by Steve Albers of course!)

Of course, the pole centered maps need no adjustment.

ie Dione centered 90N and 0W is simply entered unadjusted.

90 for latitude and any input longitude.

I hope this helps you.


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I call heaven and earth to witness against you this day, that I have set before thee life and death, the blessing and the curse; therefore choose life, that thou mayest live, thou and thy seed.

- Opening line from episode 13 of "Cosmos"
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scalbers
post Mar 17 2006, 07:24 PM
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Hi all,

It's true I use a map convention that's 180 degrees offset from Celestia. I actually routinely port my map updates into Celestia. To do this I (in a Linux environment) run the 'convert' utility with a "roll" option to offset the map. There may also be a way to make a Celestia animation that can be posted on the web, though it may be a bit tedious. Here are a couple of still images:

http://laps.noaa.gov/albers/sos/saturn/iap...tus_apr06_1.jpg

http://laps.noaa.gov/albers/sos/saturn/iap...tus_apr06_2.jpg


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angel1801
post Mar 18 2006, 12:43 PM
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QUOTE (scalbers @ Mar 18 2006, 04:54 AM) *
Hi all,

It's true I use a map convention that's 180 degrees offset from Celestia. I actually routinely port my map updates into Celestia. To do this I (in a Linux environment) run the 'convert' utility with a "roll" option to offset the map. There may also be a way to make a Celestia animation that can be posted on the web, though it may be a bit tedious. Here are a couple of still images:

http://laps.noaa.gov/albers/sos/saturn/iap...tus_apr06_1.jpg

http://laps.noaa.gov/albers/sos/saturn/iap...tus_apr06_2.jpg


Is there a "roll" option for those who use Celestia only on Microsoft Windows? Can you write a script
in Celestia for Windows to compersate for it?


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I call heaven and earth to witness against you this day, that I have set before thee life and death, the blessing and the curse; therefore choose life, that thou mayest live, thou and thy seed.

- Opening line from episode 13 of "Cosmos"
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helvick
post Mar 18 2006, 02:29 PM
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QUOTE (angel1801 @ Mar 18 2006, 12:43 PM) *
Is there a "roll" option for those who use Celestia only on Microsoft Windows? Can you write a script
in Celestia for Windows to compersate for it?

I don't think celestia can do this itself but you can also do this with any graphics editor that can load the files - just carefully split it in two and rejoin by hand.
I have a short Perl GD script that I can post that does it but you'd need Perl with the GD module installed for it to be of any use to you.
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scalbers
post Mar 18 2006, 02:54 PM
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Angel1801,

It turns out that the 'convert' utility is independent of Celestia, so I simply run this prior to copying the file into my Celestia directory. Perhaps there's a similar utility available in the Windows environment, within Photoshop or something like that?

Another option is that I might be able to mirror some of my Celestia map versions to a web-accessable directory. Hopefully the disk space would be reasonable, though if that were an issue I could always run my 2-week purger on it (relative to when I update a given image). I'll think about this some more over the next few days.


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Phil Stooke
post Mar 18 2006, 06:27 PM
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If you need to switch between maps centred at 0 and 180 longitude, the process is trivial in any image editing software like Photoshop. I would simply select the whole map, copy it and paste it over itself twice. One copy I push out half-way to the left, one half-way to the right, then zoom in and make sure they are exactly lined up with each other and with the middle column of pixels. Flatten and save.

Phil


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um3k
post Mar 19 2006, 04:51 AM
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QUOTE (Phil Stooke @ Mar 18 2006, 01:27 PM) *
If you need to switch between maps centred at 0 and 180 longitude, the process is trivial in any image editing software like Photoshop. I would simply select the whole map, copy it and paste it over itself twice. One copy I push out half-way to the left, one half-way to the right, then zoom in and make sure they are exactly lined up with each other and with the middle column of pixels. Flatten and save.

Phil

You can also use the "offset" filter. Just set it to offset it 1/2 the pixel width of the image to the right. (I hope that made sense. I'm a bit tired.)
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edstrick
post Mar 19 2006, 12:24 PM
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I flipped the meridians in an Iapetus map a while back in photoshop by using the "Image / Canvas Size" command: I reduce the image by half horizontally, cropping the right side and saving the file as "left". I reload the image and then repeat the process, cropping the left side, saving it (for safety) as "right". I re-size the canvas to enlarge the right, open select and copy the "left" image and paste it in the blank "right" area. Probably need to "flatten" the composite image.

I've never figured out how to use layers and stuff worth a damn. Lazy.
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TritonAntares
post Mar 19 2006, 06:59 PM
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Many thanks for the advices on converting the Iapetus-map from 0 to 180 center.
I will try when time allows...

Back to Iapetus...
...I found these two 'old' Cassini images back from July 19, 2004:

Attached Image

Distance: ~ 2.9 Mio. km
Resolution: 17 km/pxl

A first hint on what we'll see in the upcoming far-encounter.
Visible is the bright southern rim of the big bassin in eastern CR
and the polar region with a large amount of craters below.
Actually what is the dark curved structure parallel to the terminator?
The eastern rim of another big bassin?
There also seems to be a greater structure - possibly a crater - left to the terminator south of this dark bow.

Bye.
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scalbers
post Mar 20 2006, 08:31 PM
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Interesting images from back in 2004. I'll have to see whether they add any details beyond what I have in the map.

I have also placed some Celestia compatable versions of the Iapetus map on the web at this URL:

http://laps.noaa.gov/albers/sos/celestia


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TritonAntares
post Mar 20 2006, 11:03 PM
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QUOTE (um3k @ Mar 19 2006, 05:51 AM) *
You can also use the "offset" filter. Just set it to offset it 1/2 the pixel width of the image to the right.

I tried this...
and easy going!

Here are 3 animations for the upcoming far-encounter using this texture:
Mar 25 to 31:
Attached File  iapetus_a.avi.html ( 215.5K ) Number of downloads: 1187

Apr 01 to 12:
Attached File  iapetus_b.avi.html ( 425K ) Number of downloads: 928

Apr 12 to 18:
Attached File  iapetus_c.avi.html ( 272K ) Number of downloads: 916

Just remove *.html and run the avi-files.
I prefer running them on a DIVX-player.

Bye.
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tedstryk
post Mar 22 2006, 09:27 PM
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QUOTE (TritonAntares @ Mar 19 2006, 06:59 PM) *
Many thanks for the advices on converting the Iapetus-map from 0 to 180 center.
I will try when time allows...

Back to Iapetus...
...I found these two 'old' Cassini images back from July 19, 2004:

Attached Image

Distance: ~ 2.9 Mio. km
Resolution: 17 km/pxl


Yes...that is a sequence from slightly farther out than the one I used to make this super-res view I posted a while back.



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TritonAntares
post Mar 23 2006, 10:33 AM
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The first Iapetus image of the upcoming far-encounter has been released by NASA/JPL:
Here an enlarged part:
Attached Image
Date: March 16, 2006
Distance: 5.247.271 km (!)
Filters: CL1 & CL2
Enlargement: 3x

Don't know why they took it, probably an OPNAV.
Maybe they just wanted to know if this strange moon is still there... huh.gif blink.gif
... it is. cool.gif

Bye.
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