Celestia Forums

Posted: **18.10.2008, 18:31**

Hi folk,
someone knows what are the right parameters that I must insert in a .ssc file to have seasat1's orbit?
I have used these (I took them from Orbitron):

Code: Select all

"SeaSat1" "Sol/Earth"
{
   Class "spacecraft"
   Radius 0.00105

   EllipticalOrbit
      {
      Period 0.06934
      SemiMajorAxis 7130
      Eccentricity .0001705
      Inclination 108.006
      ArgOfPericenter 283.405
      AscendingNode 171.887
      MeanAnomaly  76.691
      Epoch 1224009217
      }   
      Albedo 0.10
}

But I think they are wrong because when I use Vincent's script to calculate RA and DEC the values don't correspond to Orbitron's values.
It seems they're looking to different things!
Thanks in advange,
Mary!

Posted: **18.10.2008, 19:03**

The epoch looks wrong--I think that Celestia and Orbitron must use a different format for it. Can you post the unmodified Orbitron data?

--Chris

Posted: **18.10.2008, 19:06**

chris wrote:The epoch looks wrong--I think that Celestia and Orbitron must use a different format for it. Can you post the unmodified Orbitron data?

--Chris

Excuse me Chris,
I don't understand... What is unmodified Orbitron data? Can you explain me?
Thx, Mary.

Posted: **18.10.2008, 19:13**

chris wrote:The epoch looks wrong--I think that Celestia and Orbitron must use a different format for it. Can you post the unmodified Orbitron data?

--Chris

I downloaded Orbitron from this site:
http://www.stoff.pl/

Posted: **18.10.2008, 22:21**

chris wrote:The epoch looks wrong--I think that Celestia and Orbitron must use a different format for it. Can you post the unmodified Orbitron data?

--Chris

Hi Chris,
is it possible that hubble's parameters are wrong?
I'm using parameters downloaded from Celestia Motherlode. I'm watching hubble orbiting and I see that it's descending instead ascending like hubble in site http://www.n2yo.com/?s=20580
How can I put hubble in the right point?

Posted: **19.10.2008, 02:46**

rinoa79 wrote:is it possible that hubble's parameters are wrong?
I'm using parameters downloaded from Celestia Motherlode.

Just FYI, it is very MUCH possible that the parameters are wrong. I don't
believe that these have been updated in a very long time now. Sorry.
Again, just FYI.

Thanks, Brain-Dead

Posted: **19.10.2008, 21:19**

rinoa79 wrote:
chris wrote:The epoch looks wrong--I think that Celestia and Orbitron must use a different format for it. Can you post the unmodified Orbitron data?

--Chris

Excuse me Chris,
I don't understand... What is unmodified Orbitron data? Can you explain me?
Thx, Mary.

I mean the values from Orbitron that you used to create the EllipticalOrbit for Celestia.

Anyhow, I don't understand how you got the Epoch. Most satellite tracking programs use the TLE (two line element) format for orbits. For a TLE, the Epoch has the form

YYDDD.TTTTT

Where YY is a two-digit year number, DDD is the day of the year, and TTTTT is a fraction of a day. In you example, the epoch is 1224009217. There's decimal point, and the first two digits indicate that the year is 2012, which seems somewhat unlikely. If we can figure out the correct epoch, I think that you'll get the right coordinates for seasat1.

--Chris

Posted: **19.10.2008, 23:41**

Thank you, Chris!
Mary

Posted: **24.10.2008, 07:14**

http://nssdc.gsfc.nasa.gov/nmc/spacecraftOrbit.do?id=1978-064A

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