Re: Possible further elset developments
Björn Gimle (b_gimle@algonet.se)
Thu, 1 Apr 1999 10:39:26 +0200
>See ftp://tie.jpl.nasa.gov/pub/dransom/current.data/flash.txt
>
The prospect of a new TLE format with a secret algorithm is not appealing.
> I have implemented new TLE processing software which checks
> the age of TLEs posted in my TLEnnn.ZIP, GSFCnnn.ZIP and
> TLyymmdd.ZIP files. TLEs are deleted which are more than 21
> to 60 days old as a function of Mean Motion; LEO satellites
> are dropped at 21 days and GEO satellites at 60 days with
> other orbits falling in between those two limits.
> ... Comments invited.
Though I rarely use the RPV BBS site nowadays, I think a general principle
for everyone who cares to add a filter to their publishing should be to
collect the (latest) elset removed from a regular file, or replaced by
a newer one, in a historical file. (NB just one per object)
The age criterion could be (DAYS/MM)*[DAYS*abs(NDOT2)+0.0008] < 0.05
This will trigger at 62.5 days for a GEO, 19 days for a LEO with a drag
term of 0.001. This will be when prediction uncertainty is about 15 min.
which will take considerably longer time than 60 days for a stable LEO.
The historical file will have the benefits of being a source for checking
possible decay observations, comparing the two latest elsets for accuracy,finding objects that need observations or elset computations...
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