Re: Mars Express TLE?

From: Björn Gimle (b_gimle@algonet.se)
Date: Thu Jun 05 2003 - 06:52:26 EDT

  • Next message: Tony Beresford: "Re: Mars Express TLE?"

    To get the CARTESIAN data you must use the telnet and/or mail access
    method. I don't know Dance of the Planets, but I suppose you should
    request GEOcentric coordinates. For using the WWW interface there ought
    to be an observatory location = Earth's Centre, but I haven't found one,
    and site elevation must be > -20 km.
    
    You can use SkyMap's starname.txt file to enter RA/Dec positions, or its
    .trj (Rocket trajectory) facility for Time/Lat/Lon/Height values.
    
    You can get RA/Dec on the WWW interface, or the 'observer' data. RA needs
    to be converted to decimal hours. The starname.txt file has no range
    info, so there is parallax for sites other than the one selected for
    ephemides. Use the apparent positions, airless (no refraction)
    
    For lat/long you can use the site's long, RA, and Apparent Siderial Time
    to compute the sub-satellite longitude. Again, this is only approximate.
    The range also needs to be converted to km, and decreased by about
    6370*(1-cos(EL)) to get height.
    
    More accurate values can be obtained from the cartesian coordinates,
    converted to angular, and adjusted by Greenwich siderial time.
    
    > JPL publishes the CARTESIAN VECTORS which you can use in the
    > planetarium program Dance of The Planets to generate ephemerides
    > and graphic views of interplanetary trajectories, flybys etc.
    > As far as I know, this old program Dance of the Planets is the
    > only "amateur consumer" software that will do this. If anyone
    > knows of a more up to date program with this ability I would
    > like to hear about it.
    
    ( http://ssd.jpl.nasa.gov/horizons.html )
    
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