Re: decoding strange 3le format

From: Jonathan McDowell via Seesat-l <>
Date: Wed, 21 May 2014 15:06:41 -0400
This is one of mine. It's a special format I use (the '2' in position
9 of line 3 denotes 'format 2', my own invention) for cases which
don't fit in the regular TLE format: specifically, where the central
body is not the Earth   (in this case the central body is 'Sun')
and/or where the
eccentricity is > 1  (not the case in this example). To accommodate
the corresponding changes in the range of e and M values, I have
added extra space in line 2 and made the decimal point explicit in the
The other fields in line 3: the "UNK" is a tag for the data source
(equal to NOR for older public NORAD TLEs and SPTR for modern,
restricted-distribution Space-Track TLEs, UNK is unknown, I have also
CSS for hobbyist elements (originally stood for Canadian
Space Society, but includes Mike McCant's classified TLEs; JCM for
approximate elsets of dubious quality that I have constructed
personally; HOR for elsets derived from JPL Horizons data and some other cases.)
The 'ELS93' is a reference for the source data file for the elset,
usually a filename on my computer that'll be no good to anyone else.
In this
case it refers to a file of heliocentric orbital elements downloaded
from the GSFC NSSDC web site in 1993.
The '3' line is distinct from the '0' line used by some other
providers; I usually don't bother with the 0 line but it is legal to
include it.

 - Jonathan

On 21 May 2014 14:49, via Seesat-l
<> wrote:
> can someone help me to figure out the following historical 3LE of ISEE-3
> (Norad 11004 COSPAR 1979-079A)? i understand that line 3 is line 0 but line
> 2 is throwing me off...
> 1 11004U 78079A   85254.41667000 0.00000000 +00000-0 +00000-0 0    19
> 2 11004   0.1232  68.5250   0.0538698 118.9910   188.6817
> 0.0028217899
> 3 11004  2 UNK     Sun                            ELS93
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Received on Wed May 21 2014 - 14:07:10 UTC

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