Celestia Forums

Finally got around to adding a lookup by HIP# feature to to the Zelestra Star System Registry.

http://www.zelestra.com/ssr/

Chris, VMF is finally out in a draft form. You can define your own model source MIME type ("application/x-celestia-3d"?), and go from there. Thought it might help if you are still looking at an XML version of .ssc. ------ Visual Model Format (VMF) is an XML document specification that is meant to pr...

If someone is interested in supplying an average Mass column to this table, I would be much obliged.

If someone is interested in supplying an average Mass column to this table, I would be much obliged.

And with a simple change of name... Voila! Thanks!

Are there any great arguments for aligning obliquity to the ecliptic rather than orbital plane?

I was twiddling with Obliquity and Longitude of Rotational Axis in the solarsys.scc and I found what appear to be anomalies (pun intended). I removed the custom orbit of Earth and changed its orbital inclination to be within the celestial equatorial plane and set its obliquity to zero. Earth's axis ...

I have been estimating Radius and Mass from Absolute Magnitude and Temperature. Lots of fun math. Radius is straight forward, but mass only works for Main Sequence Stars, which are generally 3.5 root of the luminosity. Does anyone have a formula to estimate mass for the non-main sequence luminosity ...

The XML Schema for Star System Definitions is now online at SpaceGear.Org. There are still some major pieces missing, such as a Visual Model Format file definition. But the major structure is there. Thanks to the folks at Unistellar Industries , the Zelestra Star System Registry , now sports a nice ...

I am getting about 8800 stars visible from the Sol system when Celestia is displaying stars within the visible range of magnitude. Is that about right?

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It would be nice to show how many stars are visible as you adjust the visible range parameter.

FYI: A column for average temperature has been added to the table.

Each row within the table defines an average absolute magnitude and RGB color for a specific stellar classification.

Table is available at:
http://www.spacegear.org/data/SCTable/

I am sure there is plenty of room for improvement. Suggestions welcome.

Make it possible to provide the time of periapsis as an alternative to mean anomaly and the distance at periapsis as an alternative to semi-major axis. These values are useful for describing parabolic and hyperbolic orbits (eccentricity >= 1) I have added time of periapsis passage. Distance at peri...

The Keplerian Orbit XML Schema standard is completed and is now online. Thanks to everyone who participated!

The bad: One has to parse XML (as opposed to a flat file format). It is inheirantly verbose. If one is not careful, the syntax can become confusing. Defining and indexing it is royal pain. The good: It is a standard. It uses plain text. Via XML Schema datatypes can be well defined. It is extendable ...

I am thinking of making Period optional. If it does not exist, then it is calculated from the semi-major axis and mass of the parent.
Your thoughts?

Chris, I was kinda serious about the trajectory comment. Are there really any other types of orbits other than Elliptical Keplerian Orbits? Custom orbits I don't count because they are implemented in code. Why not just call the element Orbit? (Custom orbit information could be called CustomOrbit) I ...

I think that parent should not be part of EllipticalOrbit, but Epoch should be left there . . . RotationElements should have it's own Epoch, as it's quite possible that you'd have a separate epochs for the orbit and the rotation elements. Good points. I will make the modifications when I put togeth...

Does it make sense to remove Epoch and Parent from EllipticalOrbit and place it within the enclosing element? Why? Parent makes more sense within the orbiting body representation. Luna is a child of Earth. Epoch is used by the orbiting body, for such things as rotation offset, which is not part of o...

Are there any typical rules of thumb as to when a moon or other body is in an orbital plane relative to the planet's equatorial plane or to the ecliptic? I thought moon orbits were designated as being relative to the equator of the planet that they orbit. However, it looks like Luna's orbital inclin...

One could create an ecliptic coordinate reference and just use that as the parent. This being something that can be a parent, but is not a real object. I know it seems wierd to assign obliquity to barycenter, but we will need a barycenter object anyway to have a couple objects orbiting each other at...