Satellite State Representation

class satkit.satstate(time, pos, vel, cov=None)

Bases: object

A convenience class representing a satellite position and velocity, and optionally 6x6 position/velocity covariance at a particular instant in time

This class can be used to propagate the position, velocity, and optional covariance to different points in time.

cov

6x6 state covariance matrix in GCRF frame

Returns:

• npt.ArrayLike[np.float64] | None

  6x6 numpy array representing state covariance in GCRF frame or None if not set

pos

state position in meters in GCRF frame

Returns:

• npt.ArrayLike[np.float64]

  3-element numpy array representing position in meters in GCRF frame

pos_gcrf

qgcrf2lvlh

Quaternion that rotates from the GCRF to the LVLH frame for the current state

Returns:

• satkit.quaternion

  Quaternion that rotates from the GCRF to the LVLH frame for the current state

set_gcrf_pos_uncertainty(sigma_cart)

Set position uncertainty (1-sigma, meters) in the gcrf (Geocentric Celestial Reference Frame)

Parameters:

sigma_gcrf (numpy.ndarray) – 3-element numpy array with 1-sigma position uncertainty in GCRF frame. Units are meters

Returns:

None

set_lvlh_pos_uncertainty(sigma_pvh)

Set position uncertainty (1-sigma, meters) in the lvlh (local-vertical, local-horizontal) frame

Parameters:

sigma_lvlh (numpy.ndarray) – 3-element numpy array with 1-sigma position uncertainty in LVLH frame. Units are meters

Returns:

None

time

Return time of this satellite state

Returns:

• satkit.time

  Time instant of this state

vel

Return this state velocity in meters / second in GCRF

Returns:

• npt.ArrayLike[np.float64]

  3-element numpy array representing velocity in meters / second in GCRF frame

vel_gcrf

satstate.propagate(timedur, **kwargs)

Propagates the satellite state to a target time or duration.