SkyMap vs. other tracking programs

From: Matson, Robert (
Date: Wed Jul 19 2000 - 10:10:08 PDT

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    Paul Gabriel wrote:
    > I thought that trakstar265 and skymap64 used the same orbital model
    > but skymap's prediction was about 5 sec time slow (based on the insertion
    of the time
    > on skymap trak) compared to trakstar and my obs.  not that this is a major
    > but it helps me to better plan and observe knowing that once I pick out a
    pos_obs point,
    > I should then run trakstar to get a closer estimate of the time
    Paul, if either of this programs is more accurate (which is
    doubtful for this case), it is SkyMap not Trakstar.  SkyMap's
    coding of SGP4/SDP4 has been rigorously tested and has indeed
    led to discoveries of minor coding errors BY SPACE COMMAND of
    their own publically released algorithms.  I corrected these
    errors long ago, and posted code corrections to this list
    and elsewhere.  A few have made those corrections (including
    JPL); many have not.  While this should not in general have an
    effect on predictions of LEO's like USA 129, I will guarantee
    that if any errors remain in SkyMap's coding of Space Command's
    algorithms, they are shared by ALL publically available programs.
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