Cedna & asteroid 2004 FH in Celestia

[LarsS]

Hi, when can we expect that Cedna & asteroid 2004 FH will be included in Celestia?

[t00fri]

Hi, when can we expect that Cedna & asteroid 2004 FH will be included in Celestia?

Why don't you just quickly include it yourself? That's one great thing about Celestia that users can easily "suspend" about everything in the sky they like!

The orbit data you find for example in the Sedna threat in our Physics & Astronomy department.

But I am sure many users have done all that already and you just have to wait a bit...

Bye Fridger

Addendum: I noticed that Grant put it up already in Physics & Astronomy:

You may use e.g. Amalthea's redish Texture instead...
Just add this at the end of your solarsys.ssc file.

You may search then for Sedna in the command line, hit g and you are there...

Code: Select all

"Sedna" "Sol"
 {
    Class "asteroid"
    Texture "asteroid.jpg"
    Radius 850
    Albedo 0.05
 
    EllipticalOrbit
    {
    Epoch         2453200.5 #<= Julian date
    Period         12260
    SemiMajorAxis      531.6576335
    Eccentricity      0.8574338
    Inclination      11.93041
    AscendingNode      144.49288
    ArgOfPericenter      311.82711
    MeanAnomaly      357.88147
    }
 }


[granthutchison]

And from another thread on the forum, the pre-encounter elements for 2004 FH:

Code: Select all

"2004 FH" "Sol"
{
   Class "asteroid"
   Texture "asteroid.jpg"
   Mesh "asteroid.cms"
   Radius 0.03
   
   EllipticalOrbit
   {
      Epoch 2453200.5
      SemiMajorAxis 0.81755790
      Eccentricity 0.288970015
      Inclination 0.0209936
      ArgOfPericenter 21.2277813
      AscendingNode 306.2062513
      MeanAnomaly 28.1192737
      Period 0.74
   }
}

Grant

[TERRIER]

Also not forgetting that Jestr has produced a texture and model for Sedna,
available at;

http://jestrxtras.topcities.com/index.html

or

ftp://celestia:addons@81.111.74.239/

[fsgregs]

Hi Folks:

Thanks Grant for the ssc file on 2004 FM. I plugged in the ssc values above for 2004 FM and watched it in Celestia. Its closest approach to Earth was 419,000 km. However, based on web information I examined, 2004 FM came within 43,000 km of Earth at closest approach on 3/19. That is a BIG difference. Is there a reason for the large difference in values?

Frank

[granthutchison]

Its closest approach to Earth was 419,000 km.

I don't know how you got that. In my clean Celestia installation it's about half that distance: 213690km at 00:49:30 on the 19th.
The difference is because, as I said, the elements are pre-encounter ... they therefore don't take into account the gravitational interaction of Earth and the asteroid during the close approach. You'd need an xyz to display that properly.

Grant

[selden]

Here are the Keplerian parameters for 2004 FH near perigee, obtained from Horizons.

Code: Select all

"2004 FH" "Sol"
{
   Class "asteroid"
   Texture "asteroid.jpg"
   Mesh "asteroid.cms"
   Radius 0.03

        EllipticalOrbit
        {
                Period            0.6880213223475352E+00 # calculated from SMA
                SemiMajorAxis     7.793536942970281E-01
                Eccentricity      3.482811747979895E-01
                Inclination       1.946671909304247E+00
                AscendingNode     3.581718425667979E+02
                ArgOfPericenter   3.341350155785324E+02
                MeanAnomaly       2.291733085823401E+02
                Epoch       2453083.427777778
        }
}


And, as Fridger has pointed out, all those digits of precision are, umm, not entirely accurate.

These parameters yield a closest approach of about 42,830 km at about 22:08:47 UTC on the 18th.

[JackHiggins]

Learning how to make xyz files through horizons is a fun thing to know as well, I made an xyz of the 2004 FH flyby as soon as I heard about it, and viewed a bit of it in real time as it went past.

It's a bit detailed to describe in one post, but basically download the Horizons user manual, and use the interactive telnet interface; you get very familiar with it after 3 or 4 successful uses.

[ElPelado]

Whats the adress of the site?

[selden]

http://ssd.jpl.nasa.gov/horizons.html