Re: Problems with J002E3 elements

From: Tony Beresford (aberesford@iprimus.com.au)
Date: Sat Mar 29 2003 - 17:38:20 EST

  • Next message: Ed Cannon: "Re: Problems with J002E3 elements"

    At 01:55 30/03/03, Bob King wrote:
    >Hello all,
    >Like some of you I'd like to try and see this unusual object this 
    >weekend. I went to the Project Pluto website 
    >(http://www.projectpluto.com/j002e3.htm) and used the orbital elements 
    >there to try and create a chart using my planetarium charting program 
    >MegaStar. However the value of 'a' or the semi-major axis is given in 
    >kilometers rather than as a fraction. When I convert that figure to AUs 
    >and input it into my charting program I get a value that gives me a 
    >totally incorrect position for J002E3. 
    >I'd really enjoy seeing this object and wonder if anyone can help me 
    >translate the elements correctly. Many thanks for your assistance!
    Bob, the elements given on project pluto are earth centered rather than sun centered,
    so one cant treat them like asteroid orbits. I am unfamiliar with Megastar, so I dont know
    if it has the facility to handle the usual earth satellite TLE format. As Bill Gray
    points out, and you have already been reminded, the orbit model behind the TLE format
    was never designed for such orbits, so you wont get accurte positions using it.
    However it isnt too hard to get an ephemeris correct for your location. You have a choice of
    2 services. Firstly the WWW interface of the HORIZON system at JPL http://ssd.jpl.nasa.gov/horizons.html
    or the "Space Junk" page of the Minor Plsnet Center( MPC)
    http://cfa-www.harvard.edu/iau/SpaceJunk/SpaceJunk.html
    Tony Beresford
    
    
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