There is now a Libration function in all 4 supported languages.
The returned structure contains libration angles in
ecliptic latitude and ecliptic longitude, along with
the Moon's ecliptic position and distance.
Also included is the Moon's apparent angular diameter.
All 4 languages have added a `diam_deg` field to the
structure returned by the Libration function.
It is the apparent angular diameter of the Moon as
seen from the center of the Earth, expressed in degrees.
In JavaScript and Python, throw an exception if provided
an invalid refraction option. Especially in JavaScript,
it was too easy to pass in a value like 'true', which did
not calculate refraction as expected.
I already had the function ObserverVector that converts geographic
coordinates (latitude, longitude, elevation) to an equatorial-of-date
(EQD) vector.
Now I'm in the process of adding the inverse function VectorObserver
that calculates geographic coordinates from an EQD vector.
This commit implements VectorObserver in Python.
The other languages will follow in future commits.
The motivation was from the following request:
https://github.com/cosinekitty/geocalc/issues/1
The goal is to find the near-intersection between two different lines
of sight from two different observers on the Earth's surface.
Added a demo program triangulate.py that solves this problem.
Ported conversion to/from galactic coordinates to Python.
Added unit test for new Python code.
Updated documentation for all 4 supported languages.
Fixed mistakes in JavaScript function documentation.
Now there are constants for the mean radii of Jupiter's
four major moons available in the C, C#, Python, and JavaScript
versions of Astronomy Engine.
Clarified that these are all mean radii.
Fixed some lingering "//" comments in the C code
(I want to keep ANSI C code as portable as possible.)
To assist software that wants to depict Jupiter and its 4 major moons
as they would appear in a telescope, it is important to know their
physical sizes. I already had constants for Jupiter's equatorial
and polar radii. Here I add constants for the radii of the moons
Io, Europa, Ganymede, and Callisto. They are all nearly spherical,
so a single mean radius value is sufficient.
My pydown.py custom Markdown generator was printing bogus
warnings about unknown symbol types, when it was actually
generating correct documentation for those symbols.
Eliminated the warnings, and improved the output format
for global constant documentation: no more extraneous spaces.
If there really is an undocumented symbol detected, fail the build!
Don't just print a warning that slides up the screen unnoticed.
I am starting the process of implementing calculation
of Jupiter's four largest moons: Io, Europa, Ganymede, Callisto.
This commit just contains constant declarations for the
equatorial, polar, and volumetric mean radii of Jupiter.
The positions of the moons will be related to the center
of Jupiter and be expressed in Jupiter equatorial radius units,
so I felt it would be good to give users a way to convert to
kilometers, which can in turn be converted to AU.
Python docstrings don't work for variables, so I hacked
a special comment format for helping pydown generate Markdown
text for the README.md for the exported constant KM_PER_AU,
or any other constants I may want to expose in the future.
Astronomy Engine used to use USNO historical and predictive tables,
along with linear interpolation, to calculate Delta-T values.
The problem with the USNO tables is, they did not work well outside
a few centuries around present day.
Later I replaced with Espenak & Meeus piecewise polynomials
that work over a much larger time span (thousands of years).
I just discovered there were still comments in the code referring
to the USNO models. I updated the ones I could find to reflect
the current truth about how the code works today.
This is technically a breaking change, but only for clients
that use the cartesian coordinates in an ecliptic coordinate
return type. Before now, the coordinates were just separate
floating-point members ex, ey, ez. Now they are a standard
vector type.
The purpose is to allow seamless interfacing with vector
rotation functions, and to be consistent with the equatorial
coordinate types.
Now that equatorial coordinates include both angles
and cartesian coordinates, there is no need for the
VectorFromEquator function. It has been removed
from all four supported languages.
The expression "VectorFromEquator(equ, time)" can be
replaced with "equ.vec" in any calling code.
Added global/local solar eclipse functions to topic indexes for
C#, JavaScript, and Python.
Revised wording "eclipse found may be" --> "eclipse may be".
Python:
- Added missing Attributes section in class GlobalSolarEclipseInfo.
- Added classes EclipseEvent, LocalSolarEclipseInfo.
- Added stub functions SearchLocalSolarEclipse, NextLocalSolarEclipse.
Can now calculate the heliocentric Solar System Barycenter (SSB)
and Earth/Moon Barycenter (EMB).
Changes made in C, C#, JavaScript and Python:
Added new body codes SSB, EMB.
Added support for calculating both in HelioVector functions.
Verified that all calculations match NOVAS.
Verified that all calculations match each other across languages.
Added function Time.Parse to convert a UTC date/time string
into a Time object. People should not have to keep reinventing
that wheel. I will be able to simplify astro_demo_common.py.
Currently I ignore any errors when checking the C# documentation,
because there are broken links for the rotation functions I
haven't started adding yet. I will turn that error check back on
once I finish those functions.
pydown.py now searches description text for internal links
and expands them properly for Markdown file README.md.
For example: "#Body" ==> "[`Body`](#Body)".
Fixed a couple of incorrect "Astronomy_..." names in Python docs.
Never use pound-signs inside documentation for Python return types.
Automatically create internal link just like for function parameter types.
Added special case logic in pydown.py for "Time or `None`".
Fixed minor documentation mistakes in JS version.
