DSRS: 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

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

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 as follows:

Line 1
Column	Description	Example
01	Line Number of Element Data	`[1]`
03-07	Satellite Number	`[23455]`
08	Classification (U=Unclassified)	`[U]`
10-11	International Designator (Last two digits of launch year)	`[94]`
12-14	International Designator (Launch number of the year)	`[089]`
15-17	International Designator (Piece of the launch)	`[A]`
19-20	Epoch Year (Last two digits of year)	`[97]`
21-32	Epoch (Day of the year and fractional portion of the day)	`[320.90946019]`
34-43	First Time Derivative of the Mean Motion, revolutions per day	`[ .00000140]`
45-52	Second Time Derivative of Mean Motion (decimal point assumed)	`[ 00000-0]`
54-61	BSTAR drag term (decimal point assumed) for GP4 peturbations (otherwise radiation pressure coefficient)	`[ 10191-3]`
63	Ephemeris type	`[0]`
65-68	Element number	`[ 262]`
69	Checksum (Modulo 10) (Letters, blanks, periods, plus signs = 0; minus signs = 1)	`[1]`

Line 2
Column	Description	Example
01	Line Number of Element Data	`[2]`
03-07	Satellite Number	`[23455]`
09-16	Inclination (degrees)	`[ 99.0090]`
18-25	Right Ascension of the Ascending Node (degrees)	`[272.6745]`
27-33	Eccentricity (decimal point assumed at beginning)	`[0008546]`
35-42	Argument of Perigee (degrees)	`[223.1686]`
44-51	Mean Anomaly (degrees)	`[136.8816]`
53-63	Mean Motion (revs per day)	`[14.11711747]`
64-68	Revolution number at epoch (revs)	`[14849]`
69	Checksum (modulo 10)	`[5]`

All other columns are blank or fixed.

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

This is a edited local copy of a document originally produced by:

Dr TS Kelso [TS.Kelso@celestrak.com]
Last updated: 2000 December 30 02:37 EST

Dundee Satellite Receiving Station Home Page

Send Us A Comment

Logos