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AGI.Foundation.Celestial Namespace

Contains types used in modeling characteristics of celestial objects and celestial phenomena.
Classes
  ClassDescription
Public classAtmosphericDragForce
A simple model of atmospheric drag on a body according to its coefficient of drag and reference cross-sectional area. This model does not account for aerodynamic lift and is generally used for orbiting bodies which are perturbed by the atmosphere. The details of the model are specified by choosing which density model to use for the atmosphere.
Public classAtmosphericRefractionModel
Defines a refraction model.
Public classCentralBodiesFacet
A CalculationContextFacet that holds and provides information about central bodies such as planets, moons, the sun, etc.
Public classCentralBody
A central body, such as a planet, star, asteroid, libration point, etc.
Public classCentralBodyInertialAxes
This class provides the Axes based on the STK definition of a CentralBody's Inertial Axes. The Inertial Z axis aligns with the IauOrientationAxes Z axis of the CentralBody, and the Inertial X axis aligns with the vector that is the cross product of the InternationalCelestialReferenceFrame Z axis and the IAU Z axis, evaluated at the J2000 epoch.
Public classClassicalEquationOfEquinoxes

Represents the classical equation of the equinox as defined in the Explanatory Supplement to the Astronomical Almanac. This equation has been in use for many decades. For the updated equation of equinoxes defined by the IERS in 1996, see IersTechnicalNote21. To apply this equation of equinoxes, replace the existing EquationOfEquinoxes with an instance of this class.

This class uses the existing NutationModel and PrecessionModel.

Public classConstantForce
Represents a constant force.
Public classConstantSolarGeophysicalData
Represents the solar radiation and geomagnetic flux indices as constant values.
Public classConstantWindModel
Represents a constant wind speed and direction.
Public classContinuousThrustForceModel
Represents a force generated by continuous thrust.
Public classCssiSolarGeophysicalData
Represents the solar radiation and geomagnetic flux indices as they vary over time. For more details, or to obtain updated data files, see: CSSI Space Weather Data.
Public classCode exampleEarthCentralBody
The planet Earth. You should generally obtain an instance of this class from the CentralBodiesFacet instance in the calculation context instead of creating one directly.
Public classEarthGravitationalModel1996
Provides the semimajor axis, gravitational parameter, and 2nd, 3rd, 4th, and 5th zonal harmonic coefficients for the Earth Gravitational Model of 1996 (EGM96) according to NASA Technical Publication 1998-206861.
Public classEarthGravitationalModel2008
Provides the semimajor axis, gravitational parameter, and 2nd, 3rd, 4th, and 5th zonal harmonic coefficients for the Earth Gravitational Model of 2008 (EGM2008) according to the Journal of Geophysical Research, Vol 117, Issue B4, April 2012.
Public classEarthOrientationParameters
Specifies Earth polar motion coordinates and the difference between UT1 and UTC.
Public classEarthOrientationParametersData
Specifies Earth Orientation Parameters at a specific instant.
Public classEarthOrientationParametersFile
Contains static methods to read EOP data in the Celestrak EOP data file format which is documented at https://celestrak.com/SpaceData/EOP-format.asp.
Public classEarthOrientationParametersReadOptions
Specifies options for reading an EarthOrientationParametersFile.
Public classEffectiveRadiusAtmosphericRefractionModel
The effective radius model approximates the effects of refraction by assuming that the refractive index decreases linearly with altitude. This is only valid for objects at low altitude, typically less than 8-10 km. This approximation leads to a very simple formula for the refracted elevation angle that is akin to computing the elevation angle relative to a scaled Earth surface. The Earth's radius is scaled by the effective radius factor, typically a value between 0.3 and 2 -- the most common value is 4/3. Note that the model does not provide a manner for computing the effect of refraction on the signal path length.
Public classEquationOfEquinoxes

Represents the equation of the equinox (also called the "nutation in right ascension" according to the Explanatory Supplement to the Astronomical Almanac) which defines the right ascension of the mean equinox with respect to the true equator and equinox.

The two primary theories of the equation of the equinoxes are the ClassicalEquationOfEquinoxes and the UpdatedEquationOfEquinoxes. To apply a particular theory to calculations involving the Earth, obtain an instance of the EarthCentralBody from the CentralBodiesFacet and replace the existing EquationOfEquinoxes with a new instance.

Public classForceEvaluator
Base class for evaluators created by a ForceModel to compute the force.
Public classForceModel
Represents a Newtonian force which can be used to specify the equations of motion for a mass body located by an PropagationNewtonianPoint.
Public classIau1976Precession
Provides Earth precession information according to the IAU 1976 model
Public classIau1980Nutation
Provides Earth Nutation information according to the IAU 1980 model
Public classIau2000Orientation
This is a collection of the orientation information available for central bodies. The data comes from the Report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements: 2000.
Public classIau2006Orientation
This is a collection of the orientation information available for central bodies. The data comes from the Report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements: 2006.
Public classIau2006XysData
A table of IAU2006 XYS data that is used to evaluate the transformation between the International Celestial Reference Frame (ICRF) and the International Terrestrial Reference Frame (ITRF). It is usually preferable to use the ReferenceFrame instances on EarthCentralBody rather than using this table directly.
Public classIau2009Orientation
This is a collection of the orientation information available for central bodies. The data comes from the Report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements: 2009.
Public classIauOrientationAxes
The Axes representing the orientation of a CentralBody as represented by the data from the IAU/IAG Working Group reports on rotational elements expressed in the InertialAxes of the SolarSystemBarycenter. See Iau2009Orientation for more details.
Public classIauOrientationParameters
A structure containing the orientation data computed at a particular time. The data represent the direction of the pole of rotation and the rotation about that pole.
Public classIersTechnicalNote21
Provides Earth orientation parameters according to the IERS Technical Note 21.
Public classIersTechnicalNote36RelativisticCorrectionForce
A NewtonianSpecificForce that models the first order correction to the acceleration of a space object about a CentralBody. The mathematical details for this model may be found in chapter 10 of "IERS Conventions (2010)". The model was primarily designed for artificial satellites about Earth, but may be used with any space object and any CentralBody in the solar system. The force always returns the primary contributor to the correction, the Schwarzchild field of the central body. By default, corrections for frame-dragging and precession of the geodesic are also included, but may be turned off if so desired.
Public classItuRP834Version4AtmosphericRefractionModel
ITU-R P.834-4 is the ITU recommendation concerning "Effects of tropospheric refraction on radio wave propagation." The recommendation provides an analytical formula for the refracted elevation at the ground. The higher platform is assumed to be a satellite. More information is available at ITU Radiocommunication Sector. Note that the model does not provide a manner for computing the effect of refraction on the signal path length.
Public classJplDE
The common base for classes for loading and accessing JPL DE files.
Public classCode exampleJplDE200
Represents JPL DE200 ephemeris data.
Public classCode exampleJplDE403
Represents JPL DE403 ephemeris data.
Public classCode exampleJplDE405
Represents JPL DE405 ephemeris data.
Public classCode exampleJplDE421
Represents JPL DE421 ephemeris data.
Public classCode exampleJplDE430
Represents JPL DE430 ephemeris data.
Public classJplDEFile
Provides raw access to a JPL DE file.
Public classJplDEFileEvaluator
The class returned by GetEvaluator(JplDEDataIndex, EvaluatorGroup) to allow calculation of time-varying information in the JPL DE file.
Public classLibrationModel
A model of the libration of a central body.
Public classLinkRefracted
A link between a Transmitter and Receiver that travels a refracted path. The refracted link relies on an underlying ExtensibleObject link instance as well as a AtmosphericRefractionModel refraction model as the basis for computing the refracted link. In this way, a refracted link which also accounts for light travel time can be achieved by configuring the refracted link with a LinkSpeedOfLight instance as the underlying link. Or if light travel time is not important to the analysis, the LinkInstantaneous can be used as the basis for refraction.
Public classCode exampleMoonCentralBody
The moon of the Earth. You should generally obtain an instance of this class from the CentralBodiesFacet instance in the calculation context instead of creating one directly.
Public classNutation
Holds nutation angles in longitude and in obliquity.
Public classNutationModel
A model of the nutation of a central body.
Public classPrecession
Holds precession angles.
Public classPrecessionModel
A model of the precession of a central body.
Public classResultantForceBuilder
A tool used by ForceModel objects to add their Principal and Perturbation forces to a list of forces in a resultant force.
Public classScalarAtmosphericDensity
Abstract base class for all atmospheric models used to calculate density.
Public classScalarDensityJacchia1970
Calculates atmospheric density according to the Jacchia 1970 model. The Jacchia models depend on the VectorToSun to determine the shape of the atmosphere based on incident solar radiation.
Public classScalarDensityJacchiaRoberts
Calculates atmospheric density according to the Jacchia-Roberts model. The Jacchia models depend on the VectorToSun to determine the shape of the atmosphere based on incident solar radiation.
Public classScalarDensityMsis2000

Calculates atmospheric density according to the NRLMSISE 2000 model.

MSIS 2000 is applicable from 0 km to 1000 km in altitude, and is meant for applications that reach across several atmospheric boundaries. It is not recommended for specialized tropospheric work, and if you are interested only in the thermosphere (120 km+) MSIS-86 is recommended instead.

MSIS 2000 was developed by the US Naval Research Laboratory. More information and documentation is available at http://modelweb.gsfc.nasa.gov/atmos/

Unlike other density models, this type does not make use of the VectorToSun and instead determines the shape of the atmosphere purely based on the time of day.

If available, the MSIS models will make use of the time varying daily averages for the geomagnetic flux defined by the SolarGeophysicalData instance.

Public classScalarDensityMsis86

Calculates atmospheric density according to the MSIS 1986 model.

The Mass-Spectrometer-Incoherent-Scatter-1986 (MSIS-86) neutral atmosphere model describes the neutral temperature and the densities of He, O, N2, O2, Ar, H, and N. The MSIS model is based on the extensive data compilation and analysis work of A. E. Hedin and his collaborators [A. E. Hedin et al., J. Geophys. Res. 82, 2139-2156, 1977; A. E. Hedin, J. Geophys. Res. 88, 10170- 10188, 1983; A. E. Hedin, J. Geophys. Res. 92, 4649, 1987]. MSIS-86 constitutes the upper part of the COSPAR International Reference Atmosphere (CIRA-86).

Unlike other density models, this type does not make use of the VectorToSun and instead determines the shape of the atmosphere purely based on the time of day.

If available, the MSIS models will make use of the time varying daily averages for the geomagnetic flux defined by the SolarGeophysicalData instance.

Public classScalarDensityMsis90

Calculates atmospheric density according to the MSIS 1990 model.

This method is built off of the Fortran code written by Hedin et al. It is valid over the entire atmosphere. Above 72.5 km it is basically an updated MSIS 1986 density model, below 72.5 km it is based on the MAP Handbook (Labitzke et al., 1985), supplemented by other data.

Unlike other density models, this type does not make use of the VectorToSun and instead determines the shape of the atmosphere purely based on the time of day.

If available, the MSIS models will make use of the time varying daily averages for the geomagnetic flux defined by the SolarGeophysicalData instance.

Public classScalarOccultation

A class that provides evaluators for percentage of occultation/eclipse at a position, as well as EclipseType.

The percentage runs from 0.0 (completely lit) to 1.0 (total eclipse).

Public classScalarOccultationCylindrical

Provides evaluators for percentage of occultation/eclipse at a position, as well as EclipseType using the cylindrical shadow model.

The percentage runs from 0.0 (completely lit) to 1.0 (total eclipse).

This occultation model is not nearly as accurate as ScalarOccultationDualCone, which should generally be used instead. However this cylindrical model was included for completeness.

Public classScalarOccultationDualCone

Provides evaluators for percentage of occultation/eclipse at a position, as well as EclipseType using the dual cone shadow model.

The percentage runs from 0.0 (completely lit) to 1.0 (total eclipse).

This occultation model is much more accurate than ScalarOccultationCylindrical and is the one which should be used in most cases.

Public classScalarOccultationNoShadow

This is a ScalarOccultation for use with SimpleSolarRadiationForce. This type models a lack of any shadow conditions, and is primarily intended for interplanetary missions.

The same effect can be attained by using another ScalarOccultation without any bodies added to the OccludingBodies property, however this type has also been added for convenience.

Public classScalarOccultationRegulatedDualCone

Provides evaluators for percentage of occultation/eclipse at a position, as well as EclipseType using the dual cone shadow model.

The percentage runs from 0.0 (completely lit) to 1.0 (total eclipse).

This shadow model should only be used in a SimpleSolarRadiationForce in conjunction with SolarRadiationBoundaryMitigation. It performs differently than the normal ScalarOccultationDualCone in that it treats the penumbra shadow condition as umbra, and does not allow the occultation factor to change during a propagation step. This functionality is required for correct results from the boundary mitigator, but in all other circumstances the normal dual cone occultation model should be used.

Public classSimon1994PlanetaryPositions
Provides Point instances representing the positions of the planets computed using the equations described in Simon J.L., Bretagnon P., Chapront J., Chapront-Touze M., Francou G., Laskar J., 1994, A&A 282, 663-683.
Public classSimpleSolarRadiationForce
Represents the acceleration from pressure exerted on the given reflective area at the target position.
Public classSolarGeophysicalData
This class holds information on the F10.7 solar flux and the kp and ap geomagnetic flux.
Public classSolarRadiationBoundaryMitigation
Corrects for eclipse crossings during satellite propagation.
Public classSolarSystemBarycenter
The barycenter of a solar system.
Public classSpaceControlFacilityAtmosphericRefractionModel
The Satellite Control Facility (SCF) refraction model is based upon the paper "Refraction Correction, 'RC, Refraction Addition, 'RA, Milestone 4, Model 15.3A" by A. M. Smith, Aug 1978. The 'RC model (pronounced tick-R-C) provides analytical formulas for computing the refraction angle and the refracted range (i.e., the effect of refraction on the signal path) of an observer on the ground to a satellite target. The formulas depend on the surface refractivity at the ground site.
Public classSphericalHarmonicGravity
Represents the acceleration (force for a given unit mass) at a particular point from the gravitational effects of the distribution of the Earth's mass.
Public classSphericalHarmonicGravityField
The immutable class that describes the chosen subset and configuration of spherical harmonic gravitational model.
Public classSphericalHarmonicGravityModel
Contains the coefficient data for a gravity model, either specified upon construction or read in from a file. This type is passed to a SphericalHarmonicGravityField which down selects to the desired subset of this full model, and sets other configuration options. The field is then used by SphericalHarmonicGravity in order to calculate the gravitational force.
Public classCode exampleSunCentralBody
The star at the center of our solar system. You should generally obtain an instance of this class from the CentralBodiesFacet instance in the calculation context instead of creating one directly.
Public classThirdBodyGravity
Represents the gravitational acceleration created by bodies other than the central body around which a target object is orbiting.
Public classThirdBodyGravityThirdBodyInfo
A combination of the position and gravitational parameter for a perturbing gravitational body.
Public classTwoBodyGravity
Represents the acceleration from a simple two body gravity model.
Public classUSStandardAtmosphere1976
Provides scalars that calculate values using the U.S. Standard Atmosphere model, 1976 version. This model is defined with respect to mean sea level, so you must configure the MeanSeaLevel property on EarthCentralBody before using this model.
Public classUSStandardAtmosphere1976Result
The result of the calculation.
Public classVectorRefractedDisplacement
A vector representing the refracted displacement from an initial point to a final point as both points move over time. The refracted displacement vector relies on an underlying VectorDisplacement instance as well as an AtmosphericRefractionModel as the basis for computing the refracted displacement vector. In this way, a refracted displacement vector which also accounts for light travel time can be achieved by configuring the refracted displacement vector with a VectorApparentDisplacement instance as the underlying unrefracted displacement vector. If light travel time is not important to the analysis, the VectorTrueDisplacement can be used as the basis for refraction.
Public classWindModel
Defines a wind model for an atmosphere.
Public classWorldGeodeticSystem1984
Provides the set of four World Geodetic System of 1984, WGS84 (G873), defining constants according to Table 3.1 on page 3-5 of the National Imagery and Mapping Agency Technical Report TR8350.2, Third Edition, Amendment 1, 3 January 2000.
Interfaces
  InterfaceDescription
Public interfaceIJplDEWithMoonLibrationModel
A JplDE which can return a libration model for the Moon.
Delegates
  DelegateDescription
Public delegateCentralBodyInertialAxesComputeOrientationParameters
The definition of a function which computes a set of orientation parameters.
Public delegateComputeIauOrientationParameters
The definition of a function which computes a set of orientation parameters.
Enumerations
  EnumerationDescription
Public enumerationCoefficientOfReflectivityType
Defines the type of Reflectivity Coefficient used in initializing SimpleSolarRadiationForce.
Public enumerationEclipseType
Enumerates the different types of shadowing that can occur during an eclipse.
Public enumerationJplDECentralBody
The central bodies referenced in a JPL DE file.
Public enumerationJplDEDataIndex
Indices of the data available in a JPL DE file.
Public enumerationKindOfForce
Indicates the properties of a given force to be used when distinguishing the behavior of forces when defining equations of motion.
Public enumerationRadiationVectorType
Defines the type of vector to use between the target and the illuminating body in context of scalar occultation.
Public enumerationRoleOfForce
An indication of how important a given force is in the overall composite force acting on a given object. Certain integrators will use this information to optimize the efficiency of evaluating the equations of motion during propagation of forces.
Public enumerationSphericalHarmonicsTideType
This type defines types of tidal effects used to model SphericalHarmonicGravity.