Can Barycenters have Obliquity, Rotation, etc?

General discussion about Celestia that doesn't fit into other forums.
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Chuft-Captain
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Can Barycenters have Obliquity, Rotation, etc?

Post #1by Chuft-Captain » 08.02.2006, 11:45

I need to tip the axis of a Barycenter over by 90degrees and then point it in a specified direction.
I do a similar thing with an invisible object (pseudo-barycenter) in an SSC file by specifying Obliquity and EquatorAscendingNode, which works fine.
However, I haven't found a similar way to do the same with a Barycenter.

Barycenter axes always seem to point to Ecliptic North, no matter what you do to them.

Can anyone help?
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selden
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Post #2by selden » 08.02.2006, 11:53

If they don't tip, then the code isn't there. :-(

You might try using a class invisible object instead.
Selden

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Post #3by Chuft-Captain » 08.02.2006, 12:30

Cheers Selden,

Since I posted, I think I'm pretty close to getting what I want by specifying AscendingNode of the orbiting star.

You might try using a class invisible object instead.

If only it was that easy. Unfortunately, stars cannot orbit around pseudo-barycenters.

Thanks anyway.
"Is a planetary surface the right place for an expanding technological civilization?"
-- Gerard K. O'Neill (1969)

CATALOG SYNTAX HIGHLIGHTING TOOLS LAGRANGE POINTS

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selden
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Post #4by selden » 08.02.2006, 12:34

Why not use two objects at the same location?

The barycenter for stars and the invisible object for ssc objects. Both can have the same orbital parameters, maybe scaled from au to km etc for the invisible object.
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Post #5by Chuft-Captain » 08.02.2006, 13:07

That's pretty much what I'm doing. Placing them is not a problem, you just have to get the scaling factors right. As a result, I've discovered that Celestias AU is equal to 149,597,887.6 km. ( when I used 150,000,000, things were a wee bit off. (the STC object would not be in the same place as the SSC object)

Do you happen to know if the various scaling factors used within Celestia are documented anywhere. For example I also need to knpw how many seconds there are in a year (for scaling orbital Periods). My orbital periods are only 2 minutes, so if I don't get it just right, it's soon out of sync.
"Is a planetary surface the right place for an expanding technological civilization?"
-- Gerard K. O'Neill (1969)

CATALOG SYNTAX HIGHLIGHTING TOOLS LAGRANGE POINTS

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selden
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Post #6by selden » 08.02.2006, 14:14

Sorry: they're only documented in the source code.

It's known that the LY to Parsec conversion factor is slightly wrong.
Selden


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