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Stereo A and Stereo B satellite positions

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Paradigm
2011-04-01
2012-10-09
  • Paradigm
    Paradigm
    2011-04-01

    Does anyone know of a way to add the stereo A & B locations to Stellarium? I
    have searched high and low but can't find any TLE information for those sats.
    Although there is information on the locations for these satellites; (http
    ://stereo-ssc.nascom.nasa.gov/where.shtml)

    I can't make enough sense of the information to add them as a location to view
    'from'.
    Any help would be appreciated.

     
  • Bogdan Marinov
    Bogdan Marinov
    2011-04-01

    Orbital elements are typically written in the NORAD two-line format only for
    geocentric orbits, i.e. for satellites orbiting the Earth. So Stellarium's
    Satellites plug-in works only for such satellites.

    In theory, you can add them as Solar System bodies to the ssystem.ini file,
    but that requires using heliocentric orbital elements and I don't see enough
    information on that page. Even if you find them, you'll also need to update
    the elements periodically, because AFAIK they actively change their orbits.

    On the SSC page there's a link to a directory with position vectors in
    different coordinate systems:
    http://www.srl.caltech.edu/STEREO2/Position/
    but this is not the same as orbital elements.

    Simulating the view from STEREO A/B based on that is a nice idea for a plug-
    in, but far away from our current priorities.

     
  • Bogdan Marinov
    Bogdan Marinov
    2011-04-01

    You can actually find STEREO heliocentric orbital elements in the JPL HORIZONS
    system. Here's a page in the Stellarium Wiki on how to use HORIZONS data to
    add a comet to ssystem.ini. I'm not sure how up to date it is, but in
    principle, the steps should be the same:
    http://www.stellarium.org/wiki/index.php/JPL_HORIZONS
    I'm also not sure how often the data in HORIZONS is synchronized with the
    actual position of the spacecraft.

     
  • Paradigm
    Paradigm
    2011-04-01

    Thank You for such a quick reply.
    I'm going to go check out the info you posted.
    I'll update if need be.

     
  • Paradigm
    Paradigm
    2011-04-01

    OK
    Once again! Thank You!

    I managed to put together a crude but working location model. Using the
    HORIZONS models for the Stereo A/B I was able to devise a working location (
    for one day) that appears to be somewhat accurate.


    name = Stereo A
    parent = Sun
    coord_func = comet_orbit
    orbit_Eccentricity = 5.644728875145748E-03
    radius = 1000
    oblateness = 0.0
    albedo = 0.8
    lighting = true
    halo = true
    color = 1.0,1.0,1.0
    tex_halo = star16x16.png
    tex_map = nomap.png
    orbit_TimeAtPericenter = 2455679.079693936743
    orbit_PericenterDistance = 9.563446944328300E-01
    orbit_Eccentricity = 5.644728875145748E-03
    orbit_ArgOfPericenter = 9.390469227783112E+01
    orbit_AscendingNode = 2.140480179342133E+02
    orbit_Inclination = 1.256653527067138E-01


    name = Stereo B
    parent = Sun
    coord_func = comet_orbit
    orbit_Eccentricity = 4.138493743412349E-02
    radius = 1000
    oblateness = 0.0
    albedo = 0.8
    lighting = true
    halo = true
    color = 1.0,1.0,1.0
    tex_halo = star16x16.png
    tex_map = nomap.png
    orbit_TimeAtPericenter = 2455680.154531545937
    orbit_PericenterDistance = 9.997495789900405E-01
    orbit_Eccentricity = 4.138493743412349E-02
    orbit_ArgOfPericenter = 1.469731488196327E+02
    orbit_AscendingNode = 3.364302654725290E+02
    orbit_Inclination = 2.939411391514712E-01

    Any Questions?

     
  • Bogdan Marinov
    Bogdan Marinov
    2011-04-01

    Suggestion: set the radius to 1. (I don't know if setting it to 0 is
    possible.) Otherwise, if you are trying to observe from that bodies, the view
    will be influenced by your current coordinates on the surface of the
    "planets".

     
  • Paradigm
    Paradigm
    2011-04-01

    Thanks for that suggestion.
    I did that and didn't notice anything different. I searched for Stereo B and
    then CTRL+G 'ed to assume Stereo's position.

    Note: The info I posted is only for one day (April 1, 2011). Updating as we go
    will have to do for now.

     
  • Paradigm
    Paradigm
    2011-04-01

    Correction: I didn't notice it at first, but when setting radius to 1, it
    becomoes harder to 'see' the other Stereo spacecraft on the other side of the
    sun. Setting a larger radius helps me to locate the other one easier. So it
    might be wise for the sake of simplicity to leave the radius at a larger size.

     
  • Bogdan Marinov
    Bogdan Marinov
    2011-04-01

    Ctrl+G is not the only way to switch "planets". You can select your "planet"
    in the Location window.

    Have in mind that a radius of 1000 offsets your observer location with 500 km
    from the center of the body. :)

     
  • Paradigm
    Paradigm
    2011-04-01

    I understand. Right now I'm just looking into this purely for visual reference
    and therefore it doesn't have to be that accurate.
    Although, if you wish to for the sake of 'accuracy' you could.

    Any idea how we can make a plugin with this information?

     


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