Talk:Two-line element set

Content fork
From Orbital elements. Why? In my opinion, this presentation has grown even more impenetrable than the already obscure original presentation. What, pray, do the principle authors of this article hope to convey to the general reader? Thanks. Take care. 71.247.124.10 (talk) 03:07, 1 December 2008 (UTC)


 * I agree to move TLE from Orbital elements] to this more specific page. TLE is only a format for orbital elements and should not be put into [[Orbital elements#|Orbital elements. Billyauhk (talk) 17:08, 6 May 2009 (UTC)

about TLE compatibililty with Kepler's orbit elements
Dear colleagues! Be attentive when You merge TLE format with Kepler obrits. TLE data can only be used with specific algorithms, it's parameters are not exactly ellipse ephemeris values. See ["The parameters "Inclination", "Right Ascension of the Ascending Node", "Eccentricity", "Argument of Perigee" and "Mean Anomaly" are not osculating Kepler elements but a special case of "mean elements" to be used with the SGP4 model"] at http://en.wikipedia.org/wiki/Two-line_elements Best regards, Alex. —Preceding unsigned comment added by 83.237.188.186 (talk) 13:49, 15 October 2009 (UTC)

Bug in NORAD software
User "RadioFan" removed with version 15:05, 16 June 2010 the corrected Norad FORTRAN code assuming that this could be collected from the Norad WEB page if needed. But this user missed the point that this code of Norad is not correct! According to the FORTRAN specifications it no guarantee that local variables in subroutines keep their values between calls unless this has been specified with "SAVE" specifications. Most compilers save the values anyway and this is the reason while this bug has not been observed and corrected. But for example the GNU FORTRAN compiler sticks to the official specifications and the NORAD software only works if it is corrected as follows:

SUBROUTINE SGP4(IFLAG,TSINCE) COMMON/E1/XMO,XNODEO,OMEGAO,EO,XINCL,XNO, 1          BSTAR,X,Y,Z,XDOT,YDOT,ZDOT COMMON/C1/CK2,CK4,E6A,QOMS2T,S,TOTHRD,XJ3,XKE,XKMPER,AE C C  THE FOLLOWING SAVE STATEMENTS ADDED TO THE ORIGINAL CODE C  SOME FORTRAN SYSTEM DO NOT KEEP THE VALUES OTHERWISE! C      SAVE COSIO,X3THM1,XNODP,AODP,ISIMP,ETA,C1,SINIO,X1MTH2,C4,C5 SAVE XMDOT,OMGDOT,XNODOT,OMGCOF,XMCOF,XNODCF,T2COF,XLCOF,AYCOF SAVE DELMO,SINMO,X7THM1,D2,D3,D4,T3COF,T4COF,T5COF

Certainly it would be better if Norad corrected this code specified on their WEB page themselfs!! Anybody with the necessary contacts to NORAD reading this?!

Stamcose (talk) 10:19, 9 February 2011 (UTC)


 * Wikipedia is not a publisher of original research. The observations above, true or not, are original research in the absence of references to reliable sources. I've seen Vallado's version of the code referenced far more than the NORAD code anyway.  It's what most people are likely to come across since they'll likely start at Celestrak anyway.  The code doesn't belong in this article anyway.  While, links to it are appropriate in the external links section but this isn'[t a code repository. --RadioFan (talk) 14:31, 9 February 2011 (UTC)

A section on limitations of TLE data format
TLE format has 5-digit catalog number limitation which means for 100,000 plus tracked objects an alternate system is being implemented. Then there are issues like Y2K problem for Epoch Year too. May be a new section would be useful here in educating public. Ohsin 21:49, 25 June 2020 (UTC)