pysgp4

rapper for the SGP4 propagator

Module summary

Classes

SGP4([settings])

Propagator class implementing the SGP4 propagator.

Contents

SGP4

class sorts.propagator.pysgp4.SGP4(settings=None, **kwargs)[source]

Bases: sorts.propagator.base.Propagator

Propagator class implementing the SGP4 propagator.

Frame options are found in the sorts.frames.convert function.

Variables

  • in_frame (str) – String identifying the input frame.

  • out_frame (str) – String identifying the output frame.

Parameters

  • in_frame (str) – String identifying the input frame.

  • out_frame (str) – String identifying the output frame.

TEME_to_TLE(state, epoch, B=0.0, kepler=False, tol=1e-05, tol_v=1e-07)[source]

Convert osculating orbital elements in TEME to mean elements used in two line element sets (TLE’s).

Parameters

  • kep (numpy.ndarray) – Osculating State (position and velocity) vector in m and m/s, TEME frame. If kepler = True then state is osculating orbital elements, in m and radians. Orbital elements are semi major axis (m), orbital eccentricity, orbital inclination (radians), right ascension of ascending node (radians), argument of perigee (radians), mean anomaly (radians)

  • kepler (bool) – Indicates if input state is kepler elements or cartesian.

  • epoch (astropy.time.Time) – Epoch of the orbit

  • tol (float) – Wanted precision in position of mean element conversion in m.

  • tol_v (float) – Wanted precision in velocity mean element conversion in m/s.

Returns

mean elements of: semi major axis (km), orbital eccentricity, orbital inclination (radians), right ascension of ascending node (radians), argument of perigee (radians), mean anomaly (radians)

Return type

numpy.ndarray

TEME_to_TLE_OPTIM(state, epoch, B=0.0, kepler=False, tol=1e-08, tol_v=1e-09)[source]

Convert osculating orbital elements in TEME to mean elements used in two line element sets (TLE’s).

Parameters

  • kep (numpy.ndarray) – Osculating State (position and velocity) vector in m and m/s, TEME frame. If kepler = True then state is osculating orbital elements, in m and radians. Orbital elements are semi major axis (m), orbital eccentricity, orbital inclination (radians), right ascension of ascending node (radians), argument of perigee (radians), mean anomaly (radians)

  • kepler (bool) – Indicates if input state is kepler elements or cartesian.

  • epoch0 (float) – Epoch in days since 1949 December 31 00:00 UT

  • tol (float) – Wanted precision in position of mean element conversion in m.

  • tol_v (float) – Wanted precision in velocity mean element conversion in m/s.

Returns

mean elements of: semi major axis (km), orbital eccentricity, orbital inclination (radians), right ascension of ascending node (radians), argument of perigee (radians), mean anomaly (radians)

Return type

numpy.ndarray

convert_time(t, epoch)

Convert input time and epoch variables to astropy.TimeDelta and astropy.Time variables of the correct format and scale.

get_mean_elements(line1, line2, radians=False)[source]

Extract the mean elements in SI units (a [m], e [1], inc [deg], raan [deg], aop [deg], mu [deg]), B-parameter (not bstar) and epoch from a two line element pair.

heartbeat(t, state, **kwargs)

Function applied after propagation to time t and state state, before next time step as given in the input time vector to propagate.

propagate(t, state0, epoch=None, **kwargs)[source]

Propagate a state

#TODO: UPDATE THIS DOCSTRING

All state-vector are given in SI units.

Keyword arguments contain only information needed for ballistic coefficient B used by SGP4. Either B or C_D, A and m must be supplied. They also contain a option to give angles in radians or degrees. By default input is assumed to be degrees.

Frame:

The input frame is ECI (TEME) for orbital elements and Cartesian. The output frame is as standard ECEF (ITRF). But can be set to TEME.

Parameters

  • t (float/list/numpy.ndarray/astropy.time.TimeDelta) – Time to propagate relative the initial state epoch.

  • epoch (float/astropy.time.Time) – The epoch of the initial state.

  • state0 (numpy.ndarray) – 6-D Cartesian state vector in SI-units.

  • B (float) – Ballistic coefficient

  • C_D (float) – Drag coefficient

  • A (float) – Cross-sectional Area

  • m (float) – Mass

  • radians (bool) – If true, all angles are assumed to be in radians.

  • SGP4_mean_elements (bool) – If True, the input is not cartesian state but SGP4 mean elements.

Returns

6-D Cartesian state vectors in SI-units.

propagate_mean_elements(jd0, jd_f, mean_elements, epoch0, B, **kwargs)[source]

Propagate sgp4 mean elements.

propagate_tle(t, line1, line2, **kwargs)[source]

Propagate a TLE pair