Re: Geodetic precision

From: Jonathan T Wojack (
Date: Sun Aug 19 2001 - 17:57:22 PDT

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    > Hi, yes I agree - can you tell me how I find out the datum which
    > Mapblast uses here in Europe??
    > On the other hand - as I stated before: to what accuracy do we
    > aficionados need the precision differences ??
    I've been silently watching this discussion, and my opinion is this:
    If the difference in the various geoids is < 50m, and if the error range
    in TLE's is already 500m, then I think the errors in the various geoids
    can basically be ignored.  Besides, it has been my general experience
    that even if I make predictions for a city about 10km away from my real
    position, I get the same predictions than for the dwelling in which I
    live and observe - even for Iridium flares.  At some point, I think
    positional accuracy becomes overkill.  My tolerances are:
    General prediction radius:   30 to 50 km
    Iridium flare prediction radius:   5 to 15 km
    Clock tolerance level:   10 to 30 seconds
    Those levels are for if I just want to _see_ an object under ordinary
    circumstances.  In unusual cases I may want more stringent tolerances,
    but the above is good enough for me.
    So, to put this whole e-mail down to one line:  "Close enough is good
    enough.  Now just leave it alone, or be more accurate to no visible
    Jonathan T. Wojack       
    39.706d N   75.683d W      
    4 hours behind UT (-4)
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    This archive was generated by hypermail 2b29 : Sun Aug 19 2001 - 18:31:50 PDT