How to use those commands ?

Cham · Post #1by **Cham** » 26.12.2004, 19:00

I need to understand the following rotation commands :

RotationOffset
EquatorAscendingNode

Is there a complete description somewhere ? What are the units ? How do I use those commands ? I examined the parameters in the solarsys.ssc file, but I don't understand the interpretation at all. Somebody help !

jdou · Post #2by **jdou** » 27.12.2004, 10:49

Hi, mon cousin :wink:

Take a look at this address :
http://www.celestiamotherlode.net/catalog/documentation.html

jdou

Cham · Post #3by **Cham** » 27.12.2004, 18:33

I didn't found anything specific to those two commands.

What is RotationOffset ?

maxim · Post #4by **maxim** » 27.12.2004, 19:28

What is RotationOffset ?

Rotation of the object at the time given by the epoch (1st Jan 2000 by default).

maxim

Cham · Post #5by **Cham** » 27.12.2004, 19:34

Thanks for the reply. But could you be more specific ? Can you give an example ?

If I set RotationOffest to 0, what does it means ?

What is the unit for that command ?

maxim · Post #6by **maxim** » 27.12.2004, 21:41

I got the definition from Fichiers.
I can only guess what it means, but it seems to be that, as on the epoch date every planet has a certain rotation position (given in degrees from zero meridian) pointing towards his acending node. If you set it to 0, that means, that exactly at the epoch date and time, it's zero meridian is in line with it's acending node. If you set it to another offset that means that this offsets longitude meridian is in line with his acending node at that date/time.

maxim

Guest · Post #7by **Guest** » 27.12.2004, 21:59

Cham,

Did you really read the pages 22 and 23 of the SSCGuide from Bob Hegwood ?

There are a short explains about rotateOffset and EquatorAscendingNode

jdou

Guest · Post #8by **Guest** » 27.12.2004, 23:40

http://www.shatters.net/forum/viewtopic.php?t=4941&start=19

Grant

Cham · Post #9by **Cham** » 28.12.2004, 04:12

Thanks a lot for the help guys. Now, I think I understand clearly those two commands.

But like I asked in another topic, I'm unable to make some tidal star bulges locked to another body. I have two objects (a deformed star and a black hole) rotating on a circular orbit around each other (eccentricity = 0). How can I make sure the bulges are, at Epoch, EXACTLY oriented toward the black hole ? I need the EXACT number, if everything else are set to 0 by default (at Epoch).

I made the simpler situation. The deformed star has a cigar shape, with the longer lengh along the central axis (North-South). I tilted its axis by 90 degree, using the Obliquity = 90 command, so the cigar lies in the orbital plane. Now how do I rotate the cigar axis (using the EquatorAscendingNode command) so it's oriented toward the Black Hole ? At Epoch, this one is located with every parameters set to 0.

Please ?