Re: TLE with future epoch

From: Dr. T.S. Kelso via Seesat-l <>
Date: Fri, 28 Apr 2017 23:06:47 +0000

Any TLE requires it to be propagated with the same model used in the OD process, which for all TLEs on Space Track is SGP4. Results from other propagators should not be used to assess the accuracy of the results of these propagated TLEs.

Another complication is that these future TLEs can cover a wide range of orbits as well as different propagation lengths. Because of the current problems with delays of the TLEs, we’re not seeing some of the LEO satellites in the list right now, but we have seen NOAA POES satellites with epochs > 10 days out (one of the primary reasons we monitor this data). One would have to allow for different propagation lengths and orbit regimes to properly assess accuracy and then you would still need some form of truth data to compare against.  - TS

Dr. T.S. Kelso

On 2017 Apr 28, at 07:50, Björn Gimle via Seesat-l <<>> wrote:

I trust SpaceTrack to use accurate propagation methods to arrive at the
next ascending node and produce a TLE .
But once used in cheap prediction programs, the position of the high
altitude object many days from the epoch is unreliable because of
gravitational effects from Sun and moon. Maybe Mike's int2 and int3
programs can remedy this to considerable extent?

Den 28 apr 2017 19:09 skrev "Paul Cefola via Seesat-l" <<>

It would b interesting to hear a comment on the accuracy of the TLE for the
long period orbits that are mentioned in this discussion.

Paul Cefola
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