tle_linestrings_from_orbital_parameters

cysgp4.tle_linestrings_from_orbital_parameters(unicode sat_name, int sat_nr, double mjd_epoch, double inclination_deg, double raan_deg, double eccentricity, double argument_of_perigee_deg, double mean_anomaly_deg, double mean_motion_per_day) → tuple

Generate TLE strings from orbital parameters.

See TLE line strings for a description of the two-line element format. The parameters are the Orbital/Keplarian elements and Wikipedia has a really good description what each of them means.

Note: The epoch (date/time) used in TLEs has a very strange format: first two digits are the year, next three digits are the day from beginning of year, then fraction of a day is given, e.g. 20180.25 would be 2020, day 180, 6 hours (UTC).

Parameters:

sat_namestr

The satellite name.

sat_nrstr

The satellite number.

mjd_epochfloat

The epoch of the orbital parameters as MJD [day]. The function will convert this to the TLE epoch format.

inclination_degfloat

Inclination of the orbit [deg].

raan_degfloat

Right ascension of the ascending node of the orbit [deg].

eccentricityfloat

Eccentricity of the orbit [dimensionless]. Note that in the TLE only the decimal digits are stored.

argument_of_perigee_degfloat

Argument of Perigee [deg].

mean_anomaly_degfloat

Mean anomaly of the node [deg].

mean_motion_per_dayfloat

Mean motion of the satellite [1 / day].

Returns:

tle_lines(str, str, str)

TLE tuple of the satellite, consisting of the line strings.

Examples

A simple use case would be like:

>>> from datetime import datetime
>>> import cysgp4

>>> # Define satellite orbital parameters
>>> sat_name, sat_nr = 'MYSAT', 1
>>> alt_km = 3000.  # satellite altitude
>>> mean_motion = cysgp4.satellite_mean_motion(alt_km)
>>> inclination = 10.  # deg
>>> raan = 35.  # deg
>>> eccentricity = 0.0001
>>> argument_of_perigee = 0.  # deg
>>> mean_anomaly = 112.  # deg

>>> # assume, the parameters are valid for the following time
>>> dt = datetime(2019, 11, 2, 2, 5, 14)
>>> pydt = cysgp4.PyDateTime(dt)
>>> pydt
<PyDateTime: 2019-11-02 02:05:14.000000 UTC>
>>> mjd_epoch = pydt.mjd

>>> tle_tuple = cysgp4.tle_linestrings_from_orbital_parameters(
...     sat_name,
...     sat_nr,
...     mjd_epoch,
...     inclination,
...     raan,
...     eccentricity,
...     argument_of_perigee,
...     mean_anomaly,
...     mean_motion,
...     )
>>> tle_tuple
('MYSAT',
 '1 00001U 20001A   19306.08696759  .00000000  00000-0  50000-4 0    05',
 '2 00001  10.0000  35.0000 0001000   0.0000 112.0000  9.55934723    04')