Re: Question about the age of available TLEs

From: Gavin Eadie via Seesat-l <seesat-l_at_satobs.org>
Date: Sat, 10 Feb 2018 14:12:51 -0500
> On Feb 10, 2018, at 1:25 PM, Charles Phillips <charles_at_spaceflightresearch.net> wrote:
> 
> Isn't the source of most site's TLEs the Space-Track site? I believe (as you say) that CelesTrak and Heavens-Above get TLEs from Space-Track. There is a NASA site for ISS vectors and probably a TLE as well. For the "official" satellite catalog there is not another source. 

I’m sure you are correct in saying Space-Track is the ultimate source for all TLEs, except that for the ISS.  In that case NASA offers a small sequence of TLEs (on the "state vector" page) to cover the next several days.  Heavens-Above appears to use those, and not Space-Track's.  Why they then use a TLE set with an epoch getting close to two days in the future is another question!

> That being said, the quality of TLEs from Space-Track does vary; I discard any "future epoch" TLEs that they publish. Hopefully other sites also discard those TLEs.

I tend to use Celestrak TLEs believing Kelso does a good job of dropping out anomalous elements.

> I await other comments. 

Me too, though since ISS is the only object with more than one source of elements, and not exactly hard to find during a pass, and the difference found between the two sources is minor, I’m know I’m not highlighting anything of significant practical concern!
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Received on Sat Feb 10 2018 - 13:13:35 UTC

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