Skyfield

--------------------

* Erik Tollerud contributed a fix for a deprecation warning about SSL
from the most recent versions of Python (“cafile, cpath and cadefault
are deprecated, use a custom context instead”). The file download
routine now auto-detects which mechanism your Python supports.
`363 <https://github.com/skyfielders/python-skyfield/pull/363>`_

* Added an ``elevation_m`` argument to
:meth:`~skyfield.planetarylib.PlanetaryConstants.build_latlon_degrees()`.

--------------------

* To hopefully fix the ``SSL: CERTIFICATE_VERIFY_FAILED`` errors that
some users encounter when downloading timescale files, Skyfield has
taken the risk of switching away from your system’s SSL certificates
to the certificate bundle from the ``certifi`` package.
`317 <https://github.com/skyfielders/python-skyfield/issues/317>`_

* Added a new almanac routine for finding :ref:`lunar-nodes`.
`361 <https://github.com/skyfielders/python-skyfield/issues/361>`_

* Gave geographic location objects a new ``itrf_xyz()``
method that returns their raw ITRF coordinates.
`354 <https://github.com/skyfielders/python-skyfield/issues/354>`_

* Fixed the sign of the velocity vector when two vectors are directly
geometrically subtracted.
`355 <https://github.com/skyfielders/python-skyfield/issues/355>`_

--------------------

* Deprecated the old hybrid-key satellite dictionary returned by
``load.tle()`` in favor of a simple list returned by the new
:meth:`~skyfield.iokit.Loader.tle_file()` routine.
`345 <https://github.com/skyfielders/python-skyfield/issues/345>`_

* The almanac :func:`~skyfield.searchlib.find_discrete()` routine no
longer returns extraneous values in its second return value if no
changes of state were found.
`339 <https://github.com/skyfielders/python-skyfield/issues/339>`_
`351 <https://github.com/skyfielders/python-skyfield/issues/351>`_

* Added documentation and support for computing lunar libration.
`80 <https://github.com/skyfielders/python-skyfield/issues/80>`_

----------------------

* Upgraded to a new version of the ``sgp4`` Python library that, when
possible, uses the fast official C++ implementation of SGP4.

* Added a :meth:`~skyfield.sgp4lib.EarthSatellite.find_events()` Earth
satellite method that finds the times at which a satellite rises,
culminates, and sets.

* Improved the logic behind the :doc:`almanac` routines to avoid rare
situations in which a cluster of nearly identical times would be
produced for what should really be considered a single event.
`333 <https://github.com/skyfielders/python-skyfield/issues/333>`_

* Fixed the :meth:`~skyfield.timelib.Time.utc_strftime()` method so it
does not report that every day in all of recorded history is a Monday.
`335 <https://github.com/skyfielders/python-skyfield/issues/335>`_

-----------------------

* Added basic :doc:`planetary` support, enough to compute the position
of a given latitude and longitude on the surface of the Moon.
`79 <https://github.com/skyfielders/python-skyfield/issues/79>`_
`124 <https://github.com/skyfielders/python-skyfield/issues/124>`_
`258 <https://github.com/skyfielders/python-skyfield/issues/258>`_

* Added :func:`~skyfield.almanac.oppositions_conjunctions()` for finding
the dates when a planet is at opposition and conjunction with the sun.

* Added :func:`~skyfield.trigonometry.position_angle_of()` for computing
astronomical position angles.

-----------------------

* Changed the URL for the Hipparcos catalog, because the VizieR archives
FTP server is no longer responding.
`301 <https://github.com/skyfielders/python-skyfield/issues/301>`_

* Added a :func:`~skyfield.almanac.dark_twilight_day()` function that
not only handles sunrise and sunset but also all three kinds of
twilight.
`225 <https://github.com/skyfielders/python-skyfield/issues/225>`_