Celestia Forums

I am working on a 3dimensional V838 Nebula addon
The nebula is expanding and i want to ad movement to the clouds like the spacescrafts have
How can i make that xyz file from the data folder and can it be applied to nebulas?

this is what i am talking about:
http://imgsrc.hubblesite.org/hu/db/2003 ... ts/web.jpg

Unfortunately, Celestia currently supports only static models for Deep Space objects. Orbit definitions and Beginning and Ending directives are not available for them.

You might be able to produce an adequate result by defining it as an SSC object instead. However, another gotcha is that Celestia can only draw stars and associated systems reliably to a distance of 16KLY. V838 is believed to be about 20KLY from us. But maybe that's wrong

selden wrote:Unfortunately, Celestia currently supports only static models for Deep Space objects. Orbit definitions and Beginning and Ending directives are not available for them.
...

Is this really so "unfortunate"? Would you know any reliable scientific data for DSOs over time and distance scales where Celestia is still reliable in its present mathematical formulation??

The whole point is that such an implementation would require first of all an underlying cosmological framework for the Celestia Universe including general relativity! As you know, I have advocated such an extended framework many times, but it still resides in "deep freezing" mode...

Your answer above sounded as if the devs just had forgotten somehow to implement some kind of animation feature into DSO's . This would be an exceedingly naive point of view ...

t00fri wrote: ... the Celestia Universe including general relativity!

I think it is very difficult to include space time deformation by planets, stars or black holes but it will be a very improvement for Celestia which can better simulate the "reality":!:

Fridger,

It is unfortunate that the same object controls are not available for use in all of Celestia's catalogs. So far as I'm concerned, this is a software interface issue and not a physics issue.

There are quite a few DeepSpace and Star objects which undergo well measured variations on human time scales which Celestia could display if these functions were available: variable stars like the Cephids, supernovae like SN1987a, cataclysmic variables like V838, and variable Nebulae like NGC 2261.

My understanding is that Chris is considering the possibility of merging the different types of catalogs into a single type. If this does happen, it would be possible for Celestia to display many different types of varying objects.

selden wrote:Fridger,

It is unfortunate that the same object controls are not available for use in all of Celestia's catalogs. So far as I'm concerned, this is a software interface issue and not a physics issue.

There are quite a few DeepSpace and Star objects which undergo well measured variations on human time scales which Celestia could display if these functions were available: variable stars like the Cephids, supernovae like SN1987a, cataclysmic variables like V838, and variable Nebulae like NGC 2261.

My understanding is that Chris is considering the possibility of merging the different types of catalogs into a single type. If this does happen, it would be possible for Celestia to display many different types of varying objects.

Selden,

while a correct implementation of such phenomena might be approximately possible in some very few cases, the vast majority of the observable DSO variations would first REQUIRE a cosmologically correct definition of distance and time! I hope you realize what I am talking about?

I don't see how you would imagine to realize a supernova explosion or light variations of Cepheids in a scientifically correct way that admits
also their observation from relatively close distances (following Celestia's general philosophy) . Note that I am talking here about motivations for changing the core code, not about some ficticious efforts by individual add-on creators.

I don't see this issue as mainly being a matter of implementing the same object controls.

Fridger,

I think we may be "speaking past one another" -- using the same or similar concepts to describe very different objectives. Or maybe not

I am describing a method for making it possible for Celestia to display time-variable images *representing* phenomena as seen by an observer on Earth. I agree that this is not the same as actually simulating an interaction that takes place in deep space and generating a display showing the results.

I believe that until Celestia can actually do those simulations one should still be able to create a display showing what the results of those simulations would be.

Question. Since Jupiter's orbit is VSOP87 and it shows it's "accurate" position right now, do we experience the light delay when viewing it from Earth in Celestia?

Question. Since Jupiter's orbit is VSOP87 and it shows it's "accurate" position right now, do we experience the light delay when viewing it from Earth in Celestia?

Yes!!... but it's optional Buggs. Toggle it on/off with the "-" (minus) key. You can display the light-delay with the "?" key.

To prove to yourself that this works: goto earth, then select MARS, centre it, then narrow the FOV until Mars fills a good portion of the screen. (less than 1 arcminute should do it), then toggle light-delay on/off and you'll see the (apparent) position of MARS will change.

NOTE: this is in windows, and I'm assuming the same holds for other OS's.

Works for Jupiter too!!

Chuft-Captain wrote:

Question. Since Jupiter's orbit is VSOP87 and it shows it's "accurate" position right now, do we experience the light delay when viewing it from Earth in Celestia?

Yes!!... but it's optional Buggs. Toggle it on/off with the "-" (minus) key. You can display the light-delay with the "?" key.

To prove to yourself that this works: goto earth, then select MARS, centre it, then narrow the FOV until Mars fills a good portion of the screen. (less than 1 arcminute should do it), then toggle light-delay on/off and you'll see the (apparent) position of MARS will change.

NOTE: this is in windows, and I'm assuming the same holds for other OS's.

Works for Jupiter too!!

of course, I coded it looooong time ago

You might be able to produce an adequate result by defining it as an SSC object instead. However, another gotcha is that Celestia can only draw stars and associated systems reliably to a distance of 16KLY. V838 is believed to be about 20KLY from us. But maybe that's wrong

Maybe if i am defining the clouds of the nebula as spacecrafts in a dsc (not ssc, the nebula will not be associated with a star) file so i can add movement, begining and end
I havent made any test to see if it works i am still working at the 3D model i dont even know if i can add a spacecraft definition in a dsc file
I can not upload a screenshot becouse i dont have an internet conection at home

Additional information about v838 Mon is available at http://www.aavso.org/vstar/vsots/1202.shtml

This article places it at a distance of only 7500 light years, not 20KLY.

The Hubble variable nebula is another object which changes quite rapidly over time, which might look nice in an animation.

I tried to declare the nebula as spacecraft in a dsc file and is not working (or i dont know how to give the declaration)
I will try to make it at 7500ly and define it in a ssc object
The 3D model is more dificult to build as i first belived
i will be back soon with some screenshots or questions or maybe a beta