Position of ISS

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bmeaker
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Position of ISS

Post #1by bmeaker » 18.08.2004, 20:13

I was looking at the position of the ISS according to http://science.nasa.gov/temp/StationLoc.html and I noticed it was different than the position of the one that came with Celestia and an add-on I have. The add-on is Orion_Nebula's from the Celestia Motherlode site. I was wondering if there is a way to position it in the correct place. Or if somebody has already made an ssc with it in the right place.

Thanks

Brandon

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selden
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Post #2by selden » 18.08.2004, 20:40

Celestia uses Keplerian orbital parameters to position the ISS model.

The orbit of the ISS cannot be described accurately using constant Keplerian orbital parameters. Its orbit changes continuously in ways that are almost impossible to predict due to things like atmospheric drag, light pressure, cargo ship docking, etc. If you want an accurate orbit, you'll have to update it on a daily basis.

ISS TLEs (Two Line Elements) are posted to the AMSAT SAREX mailing list regularly by "Dave Larsen PhD". See http://www.amsat.org/amsat/archive/sarex/31day/threads.html
His most recent posting was on the 16th:

Code: Select all

ISS
1 25544U 98067A   04229.23839543  .00019757  00000-0  15906-3 0  4532
2 25544  51.6323  19.1941 0005251 117.9988 304.8582 15.70921896327755


Grant Hutchison has provided a spreadsheet to convert TLEs into Celestia SSCs at http://www.lepp.cornell.edu/~seb/celestia/hutchison/spreadsheets.html#2

(added slightly later)
Don't forget that Celestia models the shape of the Earth using a spheroid. That's not accurate enough to predict the path across the sky of satellites in low Earth orbit like the ISS. You can't use Celestia to find out where to look in the sky to see the ISS.
:(
Last edited by selden on 18.08.2004, 20:49, edited 1 time in total.
Selden

Topic author
bmeaker
Posts: 8
Joined: 21.07.2004
With us: 20 years 4 months
Location: Raleigh/Charlotte, NC

Post #3by bmeaker » 18.08.2004, 20:48

Thanks. I just wasn't sure. I know what the things in the ssc are but I don't really know what to put in them to get an object in the correct place.


Brandon


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