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@dependabot dependabot bot commented on behalf of github Feb 20, 2023

Bumps astronomy-engine from 2.1.12 to 2.1.14.

Release notes

Sourced from astronomy-engine's releases.

Hour Angle

This release of Astronomy Engine includes a new function HourAngle. It calculates the hour angle of a solar system body for a given geographic location at a given time.

This release also includes demo programs to calculate true solar time from the Sun's hour angle.

True ecliptic coordinates of date

This release changes the Ecliptic functions to return true ecliptic coordinates of date instead of coordinates referenced to the mean equinox of J2000. This matters because ecliptic coordinates are often significant for physical phenomena such as eclipses, transits, lunar phases, etc.

So-called "true" coordinates correct for the following 3 variables in the orientation system:

  • Large scale precession of the Earth's axis. This is a gyrating movement over a period of approximately 26000 years.
  • Small scale nutation of the Earth's axis. This small wobbling movement has a primary periodic component of 18.6 years.
  • Obliquity drift. This is a slow change of the angle between the Earth's orbital plane and the Earth's equatorial plane. Currently the angle between the planes is decreasing at a rate of 47 arcseconds per century.

By changing the Ecliptic functions to correct for these 3 variables, the results are a better fit for calculating phenomena that depend on them.

Support for calculating mean ecliptic coordinates in the J2000 system (represented by the three-letter code ECL) still exists in the form of rotation matrix functions:

  • Rotation_ECL_EQD
  • Rotation_ECL_EQJ
  • Rotation_ECL_EQD
  • Rotation_ECL_EQJ
  • Rotation_ECL_HOR
  • Rotation_HOR_ECL

New rotation matrix functions have been added to support true ecliptic coordinates of date, with the newly added three-letter code ECT:

  • Rotation_ECT_EQD
  • Rotation_ECT_EQJ
  • Rotation_EQD_ECT
  • Rotation_EQJ_ECT

Better documentation of coordinate systems

The API documentation has been updated to clearly specify whether equatorial coordinates or ecliptic coordinates are referenced to the true equinox (corrected for both precession and nutation) or the mean equinox (corrected for precession only).

More efficient nutation

Many calculations in Astronomy Engine require calculating nutation, as mentioned above. The nutation formula was excessively slow in earlier versions. It was using the full 77-term trigonometric series IAU2000B. This has been truncated to a 5-term series, and optimized via loop unrolling, across all 5 supported programming languages. The result is still accurate within 2 arcseconds while running more than 15 times as fast.

Commits
  • 97c4d2f Version 2.1.14: added HourAngle function.
  • 42650bd Java: added true solar time demo
  • 1dcdb77 Kotlin: true solar time demo
  • 632d059 Kotlin: implemented hourAngle function.
  • 5d130f0 Missed a change to generated astronomy.ts.
  • 42c352f PY: true solar time demo
  • 9e98d0f PY: Implemented HourAngle function.
  • 41e0509 JS: true solar time demo
  • f11e2e8 JS: Implemented HourAngle function.
  • 93fb622 C#: Solar time demo using HourAngle().
  • Additional commits viewable in compare view

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Bumps [astronomy-engine](https://github.com/cosinekitty/astronomy) from 2.1.12 to 2.1.14.
- [Release notes](https://github.com/cosinekitty/astronomy/releases)
- [Commits](cosinekitty/astronomy@v2.1.12...v2.1.14)

---
updated-dependencies:
- dependency-name: astronomy-engine
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
@dependabot dependabot bot added the dependencies Pull requests that update a dependency file label Feb 20, 2023
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dependabot bot commented on behalf of github Feb 27, 2023

Superseded by #15.

@dependabot dependabot bot closed this Feb 27, 2023
@dependabot dependabot bot deleted the dependabot/npm_and_yarn/astronomy-engine-2.1.14 branch February 27, 2023 02:48
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