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Orientation nomenclature. C: EQJ/ECT rotations.

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More work standardizing the nomenclature of the
orientation systems across all language documents.

Added C functions to calculate rotation matrices
for EQJ/ECT and ECT/EQJ.
This commit is contained in:
Don Cross
2022-12-08 22:03:43 -05:00
parent 281180db24
commit 1864fa8539
14 changed files with 331 additions and 168 deletions
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@@ -52,8 +52,8 @@ To get started quickly, here are some [examples](../../demo/python/).
| [HelioVector](#HelioVector) | Calculates body position vector with respect to the center of the Sun. |
| [GeoVector](#GeoVector) | Calculates body position vector with respect to the center of the Earth. |
| [Equator](#Equator) | Calculates right ascension and declination. |
| [Ecliptic](#Ecliptic) | Converts J2000 equatorial coordinates to J2000 ecliptic coordinates. |
| [EclipticLongitude](#EclipticLongitude) | Calculates ecliptic longitude of a body in the J2000 system. |
| [Ecliptic](#Ecliptic) | Converts J2000 mean equator (EQJ) coordinates to true ecliptic of date (ECT) coordinates. |
| [EclipticLongitude](#EclipticLongitude) | Calculates true ecliptic of date (ECT) longitude for a body. |
| [Horizon](#Horizon) | Calculates horizontal coordinates (azimuth, altitude) for a given observer on the Earth. |
| [PairLongitude](#PairLongitude) | Calculates the difference in apparent ecliptic longitude between two bodies, as seen from the Earth. |
| [BaryState](#BaryState) | Calculates the barycentric position and velocity vectors of the Sun or a planet. |
@@ -131,7 +131,7 @@ To get started quickly, here are some [examples](../../demo/python/).
| -------- | ----------- |
| [SearchSunLongitude](#SearchSunLongitude) | Finds the next time the Sun reaches a specified apparent ecliptic longitude in the *true equator of date* system. |
| [Seasons](#Seasons) | Finds the equinoxes and solstices for a given calendar year. |
| [SunPosition](#SunPosition) | Calculates the Sun's apparent ecliptic coordinates as seen from the Earth. |
| [SunPosition](#SunPosition) | Calculates the Sun's apparent true ecliptic of date (ECT) coordinates as seen from the Earth. |
### Coordinate transforms
@@ -141,10 +141,10 @@ It also allows converting from a vector to spherical (angular) coordinates and b
within a given orientation. Note the 3-letter codes for each of the orientation systems;
these are used in function and type names.
- **EQJ = J2000 Mean Equator**: Uses the Earth's equator on January 1, 2000, at noon UTC.
- **EQD = Equator of Date**: Uses the Earth's equator on a given date and time, adjusted for precession and nutation.
- **ECT = True Ecliptic of Date**: Uses the true orbital plane and equator of the Earth on the given date.
- **ECL = J2000 Mean Ecliptic**: Uses the plane of the Earth's orbit around the Sun in the year 2000. The x-axis is referenced against the J2000 mean equinox.
- **EQJ = J2000 Mean Equator**: Uses the Earth's mean equator (corrected for precession but ignoring nutation) on January 1, 2000, at noon UTC. This moment in time is called J2000.
- **EQD = True Equator of Date**: Uses the Earth's equator on a given date and time, adjusted for precession and nutation.
- **ECL = J2000 Mean Ecliptic**: Uses the plane of the Earth's orbit around the Sun at J2000. The x-axis is referenced against the J2000 mean equinox.
- **ECT = True Ecliptic of Date**: Uses the true (corrected for precession and nutation) orbital plane of the Earth on the given date. The x-axis is referenced against the true equinox for that date.
- **HOR = Horizontal**: Uses the viewpoint of an observer at a specific location on the Earth at a given date and time.
- **GAL = Galactic**: Based on the IAU 1958 definition of galactic coordinates.
@@ -160,20 +160,20 @@ these are used in function and type names.
| [EquatorFromVector](#EquatorFromVector) | Given an equatorial vector, calculates equatorial angular coordinates. |
| [VectorFromHorizon](#VectorFromHorizon) | Given apparent angular horizontal coordinates, calculates horizontal vector. |
| [HorizonFromVector](#HorizonFromVector) | Given a vector in horizontal orientation, calculates horizontal angular coordinates. |
| [Rotation_EQD_EQJ](#Rotation_EQD_EQJ) | Calculates a rotation matrix from equator of date (EQD) to J2000 mean equator (EQJ). |
| [Rotation_EQD_ECT](#Rotation_EQD_ECT) | Calculates a rotation matrix from equator of date (EQD) to true ecliptic of date (ECT). |
| [Rotation_EQD_ECL](#Rotation_EQD_ECL) | Calculates a rotation matrix from equator of date (EQD) to ecliptic J2000 (ECL). |
| [Rotation_EQD_HOR](#Rotation_EQD_HOR) | Calculates a rotation matrix from equator of date (EQD) to horizontal (HOR). |
| [Rotation_EQJ_EQD](#Rotation_EQJ_EQD) | Calculates a rotation matrix from J2000 mean equator (EQJ) to equator of date (EQD). |
| [Rotation_EQJ_ECL](#Rotation_EQJ_ECL) | Calculates a rotation matrix from J2000 mean equator (EQJ) to ecliptic J2000 (ECL). |
| [Rotation_EQD_EQJ](#Rotation_EQD_EQJ) | Calculates a rotation matrix from true equator of date (EQD) to J2000 mean equator (EQJ). |
| [Rotation_EQD_ECT](#Rotation_EQD_ECT) | Calculates a rotation matrix from true equator of date (EQD) to true ecliptic of date (ECT). |
| [Rotation_EQD_ECL](#Rotation_EQD_ECL) | Calculates a rotation matrix from true equator of date (EQD) to J2000 mean ecliptic (ECL). |
| [Rotation_EQD_HOR](#Rotation_EQD_HOR) | Calculates a rotation matrix from true equator of date (EQD) to horizontal (HOR). |
| [Rotation_EQJ_EQD](#Rotation_EQJ_EQD) | Calculates a rotation matrix from J2000 mean equator (EQJ) to true equator of date (EQD). |
| [Rotation_EQJ_ECL](#Rotation_EQJ_ECL) | Calculates a rotation matrix from J2000 mean equator (EQJ) to J2000 mean ecliptic (ECL). |
| [Rotation_EQJ_HOR](#Rotation_EQJ_HOR) | Calculates a rotation matrix from J2000 mean equator (EQJ) to horizontal (HOR). |
| [Rotation_ECT_EQD](#Rotation_ECT_EQD) | Calculates a rotation matrix from true ecliptic of date (ECT) to equator of date (EQD). |
| [Rotation_ECL_EQD](#Rotation_ECL_EQD) | Calculates a rotation matrix from ecliptic J2000 (ECL) to equator of date (EQD). |
| [Rotation_ECL_EQJ](#Rotation_ECL_EQJ) | Calculates a rotation matrix from ecliptic J2000 (ECL) to J2000 mean equator (EQJ). |
| [Rotation_ECL_HOR](#Rotation_ECL_HOR) | Calculates a rotation matrix from ecliptic J2000 (ECL) to horizontal (HOR). |
| [Rotation_HOR_EQD](#Rotation_HOR_EQD) | Calculates a rotation matrix from horizontal (HOR) to equator of date (EQD). |
| [Rotation_ECT_EQD](#Rotation_ECT_EQD) | Calculates a rotation matrix from true ecliptic of date (ECT) to true equator of date (EQD). |
| [Rotation_ECL_EQD](#Rotation_ECL_EQD) | Calculates a rotation matrix from J2000 mean ecliptic (ECL) to true equator of date (EQD). |
| [Rotation_ECL_EQJ](#Rotation_ECL_EQJ) | Calculates a rotation matrix from J2000 mean ecliptic (ECL) to J2000 mean equator (EQJ). |
| [Rotation_ECL_HOR](#Rotation_ECL_HOR) | Calculates a rotation matrix from J2000 mean ecliptic (ECL) to horizontal (HOR). |
| [Rotation_HOR_EQD](#Rotation_HOR_EQD) | Calculates a rotation matrix from horizontal (HOR) to true equator of date (EQD). |
| [Rotation_HOR_EQJ](#Rotation_HOR_EQJ) | Calculates a rotation matrix from horizontal (HOR) to J2000 equatorial (EQJ). |
| [Rotation_HOR_ECL](#Rotation_HOR_ECL) | Calculates a rotation matrix from horizontal (HOR) to ecliptic J2000 (ECL). |
| [Rotation_HOR_ECL](#Rotation_HOR_ECL) | Calculates a rotation matrix from horizontal (HOR) to J2000 mean ecliptic (ECL). |
| [Rotation_EQJ_GAL](#Rotation_EQJ_GAL) | Calculates a rotation matrix from J2000 mean equator (EQJ) to galactic (GAL). |
| [Rotation_GAL_EQJ](#Rotation_GAL_EQJ) | Calculates a rotation matrix from galactic (GAL) to J2000 mean equator (EQJ). |