Celestia Forums

Asteroid 2004 FH near-miss flyby. How does one get the data on this asteroid's path and orbit? And how do you turn that into an SSC file? It would be interesting to put the correct date & time into Celstia and perhaps see it whiz by so close and then turn on display asteroid orbits and see where it's been, is going and maybe when it will be back.

Interesting stuff. Thanks for any help with this.

One source of orbit elements for near-Earth asteroids is NeoDys at
http://newton.dm.unipi.it/cgi-bin/neodys/neoibo?

In particular, see
http://newton.dm.unipi.it/cgi-bin/neodys/neoibo?objects:2004FH;main

Another source would be the official Minor Planets Circulars at http://cfa-www.harvard.edu/iau/mpc.html

One description of how to translate standard astronomical orbit announcements into Celestia's SSC format is at http://www.lns.cornell.edu/~seb/celestia/transforming_ephemeris.html

I added the asteroid to Starry nigth using orbital parameters taken from a NEA Orbital Elements page cause i wanted to see it with my telescope, but its below the horizon now...
I think all these is before the orbit change that it will suffer from us....


Hope it helps

Thank you so much seldon & ElPelado for the quick responses. I did finally find the orbital info on NASA's Near Earth Objects Program website http://neo.jpl.nasa.gov/cgi-bin/neo_elem. Thank you for putting that same info into Celestia can use, ElPelado. I need to go to that link on how to translate standard astronomical orbit announcements, thanks seldon.

And now....to finish this project..... even though the asteroid's orbit is going to change due to an approx 15 degree trajectory caused by Earth.

The orbit looks right, it intersects with Earth, etc., but the object itself is no where near Earth, it is about 1/4 an orbit around Sol away from Earth at this date. Can anyone help?

Here is what I inserted into solarsys.ssc

"2004 FH" "Sol"
{
Class "asteroid"
Texture "asteroid.jpg"
Radius 1737 # should be 0.03

EllipticalOrbit
{
Epoch 53200
SemiMajorAxis 0.81755790
Eccentricity 0.288970015
Inclination 0.0209936
ArgOfPericenter 21.2277813
AscendingNode 306.2062513
MeanAnomaly 28.1192737
PericenterDistance 0.5813
Period 0.74
}
# Aphelion distance of the orbit(AU): 1.054
# Absolute V-magnitude: 25.96
}

It would be a good idea to have two orbits, one for before the close encounter and another one for after it plus a xyz file for the time around it.
I tried to add 90 and then 180 to the mean anomaly and got it closer with the addition of 180 degrees, but it doesn't get close enough.

Brendan

bassrat wrote:The orbit looks right, it intersects with Earth, etc., but the object itself is no where near Earth, it is about 1/4 an orbit around Sol away from Earth at this date. Can anyone help?

Here is what I inserted into solarsys.ssc

"2004 FH" "Sol"
{
Class "asteroid"
Texture "asteroid.jpg"
Radius 1737 # should be 0.03

EllipticalOrbit
{
Epoch 53200
SemiMajorAxis 0.81755790
Eccentricity 0.288970015
Inclination 0.0209936
ArgOfPericenter 21.2277813
AscendingNode 306.2062513
MeanAnomaly 28.1192737
PericenterDistance 0.5813
Period 0.74
}
# Aphelion distance of the orbit(AU): 1.054
# Absolute V-magnitude: 25.96
}

I think the problem is the Epoch:
I said: Epoch (TDB=Julian date - 2400000.5): 53200 TDB
You need to translate the 53200 TDB to julian date, so
53200+2400000.5=2453200,5
Try with this Epoch....

Thats worked, I tryed it my self using the Epoch I gave in the last post, so use that one:

It works!!!! I can see it, even when I size 2004FH down to it's proper size.
Thank you very much ElPelado. You have been a great help. I have a lot to learn about this stuff, including that confusing time issue.

What a delight to have gotten this to work.