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RE: Differences in tracking software



Depending on how far out they are, the differences may be explained by the
orbit propagator used.  Most amateur programs (and many others) use a
simplified version of the SGP4 propagator that doesn't account for many of
the smaller disturbances.  This is generally fine for amateur use and if the
keps are kept reasonably up to date there is very little difference in any
case.  NORAD keps are designed to work with the full SGP4 model, and
therefore the best answer will be obtained using a program that uses this
model.

Chris G7UPN

-----Original Message-----
From: KF4FDJ (Mike in Ft. Myers, FL) [mailto:seven77@gate.net]
Sent: 05 July 1999 12:59
To: AMSAT-BB@AMSAT.Org
Subject: [amsat-bb] Differences in tracking software


Steve,

Just for grins, I tried 5 different tracking programs at the same time. 
All were running the same keps.  All showed different positions.  

I've noticed this before.  I know some programs are looking for your QTH
coordinates in DD.MM.SS, while other's look for the coordinates in a
decimal format.  There is some ambiguity here, and *MIGHT* explain your
difference, if you don't have it in the form the program seeks.  But,
from my experience, NONE of them agree!

73, Mike


Steve H.- KF4FQT wrote:
>  I am using a WinOrbit in Windows 95.  I have noted that J-Track on the
> web does not show the same positions as the WinOrbit program.  That
> gives...who is right ?  I have loaded keps from AMSAT and the whole
> "nine yards".    Offset is set to -5 for southeast US.  Any help would
> be appreciated.
>     Thanks,
>         Steve H.- KF4FQT

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