opihiexarata.orbit.solution module

The orbit solution class.

class opihiexarata.orbit.solution.OrbitalSolution(observation_record: list[str], solver_engine: OrbitEngine, vehicle_args: dict = {})[source]

Bases: ExarataSolution

This is the class which solves a record of observations to derive the orbital parameters of asteroids or objects in general. A record of observations must be provided.

semimajor_axis

The semi-major axis of the orbit solved, in AU.

Type:: float

semimajor_axis_error

The error on the semi-major axis of the orbit solved, in AU.

Type:: float

eccentricity

The eccentricity of the orbit solved.

Type:: float

eccentricity_error

The error on the eccentricity of the orbit solved.

Type:: float

inclination

The angle of inclination of the orbit solved, in degrees.

Type:: float

inclination_error

The error on the angle of inclination of the orbit solved, in degrees.

Type:: float

longitude_ascending_node

The longitude of the ascending node of the orbit solved, in degrees.

Type:: float

longitude_ascending_node_error

The error on the longitude of the ascending node of the orbit solved, in degrees.

Type:: float

argument_perihelion

The argument of perihelion of the orbit solved, in degrees.

Type:: float

argument_perihelion_error

The error on the argument of perihelion of the orbit solved, in degrees.

Type:: float

mean_anomaly

The mean anomaly of the orbit solved, in degrees.

Type:: float

mean_anomaly_error

The error on the mean anomaly of the orbit solved, in degrees.

Type:: float

true_anomaly

The true anomaly of the orbit solved, in degrees. This value is calculated from the mean anomaly.

Type:: float

true_anomaly_error

The error on the true anomaly of the orbit solved, in degrees. This value is calculated from the error on the mean anomaly.

Type:: float

epoch_julian_day

The epoch where for these osculating orbital elements. This value is in Julian days.

Type:: float

__calculate_eccentric_anomaly() → tuple[float, float]

Calculating the eccentric anomaly and error from the mean anomaly.

Parameters:

None –

Returns:

eccentric_anomaly (float) – The eccentric anomaly as derived from the mean anomaly.
eccentric_anomaly_error (float) – The eccentric anomaly error derived as an average from the upper and lower ranges of the mean anomaly.

__calculate_true_anomaly() → tuple[float, float]

Calculating the true anomaly and error from the eccentric anomaly.

Parameters:

None –

Returns:

true_anomaly (float) – The true anomaly as derived from the mean anomaly.
true_anomaly_error (float) – The true anomaly error derived as an average from the upper and lower ranges of the eccentric anomaly.

__init__(observation_record: list[str], solver_engine: OrbitEngine, vehicle_args: dict = {}) → None[source]

The initialization function. Provided the list of observations, solves the orbit for the Keplarian orbits.

Parameters:

observation_record (list) – A list of the standard MPC 80-column observation records. Each element of the list should be a string representing the observation.
solver_engine (OrbitEngine) – The engine which will be used to complete the orbital elements from the observation record.
vehicle_args (dictionary) – If the vehicle function for the provided solver engine needs extra arguments not otherwise provided by the standard input, they are given here.

Return type:

None

opihiexarata.orbit.solution._calculate_eccentric_anomaly(mean_anomaly: float, eccentricity: float) → float[source]

Calculate the eccentric anomaly from the mean anomaly and eccentricity of an orbit. This is found iteratively using Newton’s method.

Parameters:: mean_anomaly (float) – The mean anomaly of the orbit, in degrees.
Returns:: eccentric_anomaly – The eccentric anomaly as derived from the mean anomaly, in degrees.
Return type:: float

opihiexarata.orbit.solution._calculate_true_anomaly(eccentric_anomaly: float, eccentricity: float) → float[source]

Calculate the true anomaly from the mean anomaly and eccentricity of an orbit.

We use the more numerically stable equation from https://ui.adsabs.harvard.edu/abs/1973CeMec…7..388B.

Parameters:: eccentric_anomaly (float) – The eccentric anomaly of the orbit, in degrees.
Returns:: true_anomaly – The true anomaly as derived from the eccentric anomaly, in degrees.
Return type:: float

opihiexarata.orbit.solution._vehicle_custom_orbit(observation_record: list[str], vehicle_args: dict) → dict[source]

This is the vehicle function for the specification of a custom orbit.

A check is done for the extra vehicle arguments to ensure that the orbital elements desired are within the arguments. The observation record is not of concern for this vehicle.

Parameters:

observation_record (list) – The MPC standard 80-column record for observations of the asteroid by which the orbit shall be computed from.
vehicle_args (dict) – The arguments to be passed to the Engine class to help its creation and solving abilities. In this case, it is just the orbital elements as defined.

opihiexarata.orbit.solution._vehicle_orbfit_orbit_determiner(observation_record: list[str]) → dict[source]

This uses the Orbfit engine to calculate orbital elements from the observation record. The results are then returned to be managed by the main class.

Parameters:: observation_record (list) – The MPC standard 80-column record for observations of the asteroid by which the orbit shall be computed from.
Returns:: orbit_results – The results of the orbit computation using the Orbfit engine. Namely, this returns the 6 classical Kepler elements, using mean anomaly.
Return type:: dict