International Best Practice for using Two Line Element Sets
- Paper number
IAC-06-C1.P.5.03
- Author
Dr. Paul Crawford, University of Dundee, United Kingdom
- Coauthor
Mr. David Vallado, United States
- Coauthor
Dr. Richard Hujsak, United States
- Coauthor
Dr. T.S. Kelso, United States
- Coauthor
Dr. Peter Mendham, University of Dundee, United Kingdom
- Year
2006
- Abstract
Over a quarter century ago, the US government (USG) performed a prediction compatibility test with recipients of two line element sets (TLEs). The test revealed that many recipients were not obtaining accurate predictions from the element sets because they used some physical constants or model other than the NORAD SGP or SGP4/SDP4. To allow all recipients to best use the data, the USG authorized unlimited public distribution of both the equations and source code used to predict satellite positions in their space surveillance system (Hoots et al., 1980, commonly called SpaceTrack Report Number 3). Since then, the USG has been the primary source of openly available orbital data, in the form of TLEs, which have become the international de facto standard for low precision orbital modelling. From the 1980s, it is widely understood that several code changes were made to improve accuracy and to handle rare cases encountered in operations. Since the modified USG code is not widely available, the code used today to produce TLEs and the code most users employ to propagate TLEs do not match, introducing errors. Technical papers, and independent source code development and testing over the past decades have enabled us to produce a publicly available implementation of the SGP4 model which we believe is up to date. This paper provides source code, test cases, results, and analysis of the implementation believed to be compatible with the operational USG code. This will permit improved accuracy and consistency for the numerous non-USG users world-wide that routinely employ TLE data.
- Abstract document
- Manuscript document
IAC-06-C1.P.5.03.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.