NORAD Two-Line Element Set Format

Data for each satellite consists of three lines in the following format:

AAAAAAAAAAAAAAAAAAAAAAAA
1 NNNNNU NNNNNAAA NNNNN.NNNNNNNN +.NNNNNNNN +NNNNN-N +NNNNN-N N NNNNN
2 NNNNN NNN.NNNN NNN.NNNN NNNNNNN NNN.NNNN NNN.NNNN NN.NNNNNNNNNNNNNN

Line 0 is a twenty-four character name (to be consistent with the name length in the NORAD SATCAT).

Lines 1 and 2 are the standard Two-Line Orbital Element Set Format identical to that used by NORAD and NASA. The format description is:

Line 1
Column Description
01 Line Number of Element Data
03-07 Satellite Number
08 Classification (U=Unclassified)
10-11 International Designator (Last two digits of launch year)
12-14 International Designator (Launch number of the year)
15-17 International Designator (Piece of the launch)
19-20 Epoch Year (Last two digits of year)
21-32 Epoch (Day of the year and fractional portion of the day)
34-43 First Time Derivative of the Mean Motion
45-52 Second Time Derivative of Mean Motion (decimal point assumed)
54-61 BSTAR drag term (decimal point assumed)
63 Ephemeris type
65-68 Element number
69 Checksum (Modulo 10)
(Letters, blanks, periods, plus signs = 0; minus signs = 1)
Line 2
Column Description
01 Line Number of Element Data
03-07 Satellite Number
09-16 Inclination [Degrees]
18-25 Right Ascension of the Ascending Node [Degrees]
27-33 Eccentricity (decimal point assumed)
35-42 Argument of Perigee [Degrees]
44-51 Mean Anomaly [Degrees]
53-63 Mean Motion [Revs per day]
64-68 Revolution number at epoch [Revs]
69 Checksum (Modulo 10)

All other columns are blank or fixed.

Example:

NOAA 14                 
1 23455U 94089A   97320.90946019  .00000140  00000-0  10191-3 0  2621
2 23455  99.0090 272.6745 0008546 223.1686 136.8816 14.11711747148495

For further information, see "Frequently Asked Questions: Two-Line Element Set Format" in the Computers & Satellites column of Satellite Times, Volume 4 Number 3.


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