Re: significantly different predictions by different programs

From: Bruce MacDonald (
Date: Mon Oct 30 2006 - 16:06:04 EST

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    Ed Cannon wrote:
    > It has come to my attention that among the programs being used for
    > predictions, there are some significantly differing results for
    > at least some objects.  A specific case is ETS 6 (94-56A, 23230).
    > Orbitron and Heavensat gave predictions that were something like
    > one hour of RA different from what Highfly predicted, which is
    > certainly enough to cause an observer to miss an observation.
    > I've never used the first two programs but, with all due respect
    > to all the programmers and program users, if there's a significant
    > difference from what Highfly predicts, I believe Highfly.
    > My point is that perhaps people who are qualified to do so might
    > compare the program predictions against observations and/or also
    > the prediction models used, in order to determine what is the
    > origin of such significant differences in predictions and which
    > predictions are most accurate.
    I've not run A/B comparisons of satellite prediction software like this - I 
    use Rob Matson's Skymap 6.6 and I'm happy with it, though I also run 
    Orbitron for ground tracks.
    Could the difference result from the Orbitron and Heavensat using the SGP4 
    algorithm, and Highfly using the SDP4 algorithm?  That may account for the 
    significant difference in predictions.
    This is an area I think we would all be interested in.  Perhaps someone 
    might try running some benchmarking tests, as Ed suggests?
    I'll have a go running some predictions of classified objects using both my 
    programs to see what happens.
    Bruce MacDonald
    COSPAR Site 2751
    Devizes, Wiltshire, United Kingdom
    51.3440 N 1.9849 W 125M (WGS 84) 
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