DSC and STC coordinates

[fsgregs]

Hi. I need someone's help. I am trying to create a new star in space (a new Black hole) without the accretion disk. I want to surround it with one of Jestr's great new 3D nebula, so that you have to pass through the wispy supernova remnants before reaching the Black Hole.

My strategy is to first create a new tiny star using an stc file. I did so successfully, calling it HIP 600108. Here is its stc entry.

600108 "Black Hole 108"
{
RA 30.00000
Dec 80.00000
Distance 900
SpectralType "Q"
AbsMag 30
}

It works fine and I can go to it, finding a tiny star with a radius of 0 and a magnitude of 30.

Next, I created the black hole around it with an ssc file, by simply placing a "black" planet onto star HIP 600108, with a radius bigger than the star and a semimajor axis of 1e-10. This too works and the black hole covers star 600108 fine.

MY problem is with the nebula. I created a dsc file to place the nebula in the same spot in space as star hip 600108, using the same coordinates. Here is the dsc entry:

Nebula "Black Hole Nebula"
{
Mesh "sigsco.cmod"
Emissive true
RA 30.00000
Dec 80.00000
Distance 900

Radius 8.0
}

All the model and texture files are in the right folders and when I go to the Black Hole Nebula, it displays fine, but it is located in a completely different spot in space, 156 light years from HIP 600108 and my black hole.

Are dsc coordinates treated differently from stc coordinates? If so, could someone please tell me how to get the center of the nebula centered on my new star?

Thanks

Frank

WHY???? HELP

[selden]

Frank,
You wondered

Are dsc coordinates treated differently from stc coordinates?

Yes.

The RA in a DSC catalog must be specified in Hours.
The RA in an STC catalog must be specified in Degrees.

Chris has regretted this decision, but it's too late now. Maybe some future version of Celestia might make it possible to specify which units you're using.

To convert from degrees to hours, divide the number of degrees by 15.
To convert from hours to degrees, multiply by 15.

I hope this clarifies things.
_________________

[fsgregs]

Dear Selden:

Yep! That did it. Everything looks fine. Here is a screenshot.



I placed two of Jestr's three nebula at the location so it glows in two colors. It is really cool in that Jestr's great nebula are immersively 3D and you can fly through them to reach the Black Hole, which is glowing with X-rays from gas plasma accelerating near the event horizon.

I will upload the add-on to Motherlode in the next few days. Look for it as the "Black Hole 108 Nebula