Copyright ©1993 - 1999 by Howard R. Cole. All Rights Reserved.
Data File Formats Rendezvous is capable of using several different coordinate systems in its calculations. The file formats for each of these systems is described below: Two Line Element Format (tle) |
o | Files with .tle extension are NORAD two line element sets. The following excerpt describing the format is taken from a posting by T.S. Kelso to the Usenet "sci.space.new" newsgroup: | |
Data for each satellite consists of three lines in the following format: |
AAAAAAAAAAA 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 1 is an eleven-character name. Lines 2 and 3 are the standard Two-Line Orbital Element Set Format identical Line 1 |
34-43 | First Time Derivative of the Mean Motion or Ballistic Coefficient (Depending on ephemeris type) |
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54-61 | BSTAR drag term if GP4 general perturbation theory was used. Otherwise, radiation pressure coefficient. (Decimal point assumed) |
![]() ![]() ![]() Line 2 |
01-01 | 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] | |
69-69 | Check Sum (Modulo 10) |
All other columns are blank or fixed.
Example: NOAA 6 |
Earth Centered Rotating Format (ecr) |
o | Files with an ecr extension are Earth Centered Rotating state vectors. A sample file would look like this: |
7 11 1991
18 40 0.0
SAT 1
0.0 2000000.0 35.083 -106.65 6900.0 0.0 0.0
SAT 2
0.0 2000000.0 42.129 -120.72 6840.0 0.0 -5.38
The first two lines contain the date and time of the epoch in free format (any number of white space characters can separate the fields).
The third and fourth line and subsequent pairs of lines contain the name for the state (this is the name that will appear in the browser), and the state itself with these fields in free format: |
SatName
timeOffset altitude latitude longitude speed ascent_angle course
The timeOffset value is the number of seconds from the epoch date at which the state is valid.
The next three numbers indicate the position of the satellite as altitude, latitude, and longitude. The altitude is measured in meters, and the latitude and longitude are measured in decimal degrees. The next three numbers indicate the velocity of the satellite as the speed, the ascent angle, and the course measured from true north. The speed is given in meters/second, and the ascent and course angles are given in decimal degrees. |
Earth Centered Inertial Format (eci)
o Files with an eci extension are Earth Centered Inertial J2000 state vectors. The first two lines are the date and time of the epoch and have the same format as the .ecr files. |
Each additional entry consists of two lines, the name of the satellite and its state vector. These entries have this format: |
SatName
timeOffset x y z vx vy vz
Again, the timeOffset is the number of seconds from the epoch date at which the state is valid.
The next three numbers (x y z) indicate the position of the satellite as cartesian components in the ECI J2000 coordinate system given in units of meters. The next three numbers (vx vy vz) indicate the velocity of the satellite as cartesian components in the ECI J2000 coordinate system given in units of meters/second. |
Element Set Format (element)
Heliocentric Ecliptic (hce) |