Skyfield

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

* An attempt at overly clever scripting resulted in a Skyfield 1.43
release without a ``setup.py`` in its ``.tar.gz``; within an hour, a
Python 2.7 user had reported that Skyfield could no longer install.
This release is identical to 1.43 but (hopefully) installs correctly
for everyone!

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

* Fixed :func:`~skyfield.magnitudelib.planetary_magnitude()` so it works
for Saturn even when the time is an array rather than a single time;
also, improved its calculation slightly with respect to Uranus.
`739 <https://github.com/skyfielders/python-skyfield/issues/739>`_

* Improved :func:`~skyfield.data.mpc.load_comets_dataframe()` so that
parsing ``CometEls.txt`` with the most recent version of Pandas
doesn’t stumble over the commas in the final field of (for example)
Halley’s Comet and give the error ``ParserError: Error tokenizing
data. C error: Expected 12 fields…saw 13``.
`707 <https://github.com/skyfielders/python-skyfield/issues/707>`_

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

* Added two new position methods
:meth:`~skyfield.positionlib.ICRF.phase_angle()`
and
:meth:`~skyfield.positionlib.ICRF.fraction_illuminated()`
that, given an illuminator (usually the Sun) as their argument,
compute whether the observer is looking at the bright side or the dark
side of the target body.
They replace a pair of old functions in the almanac module.

* The almanac routine :func:`~skyfield.almanac.moon_nodes()` would
sometimes skip nodes that were closer together than 14.0 days. It has
been tightened down and should now detect all lunar nodes.
`662 <https://github.com/skyfielders/python-skyfield/issues/662>`_

* Time objects now feature a :meth:`~skyfield.timelib.Time.to_astropy`
method.

* The position method :meth:`~skyfield.positionlib.ICRF.to_skycoord` now
sets the ``frame`` attribute of the sky coordinate it returns, and for
now only supports barycentric and geocentric positions.
`577 <https://github.com/skyfielders/python-skyfield/issues/577>`_

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

* Times now support arithmetic: you can add or subtract from a time
either a number representing days of Terrestrial Time (TT) or a Python
``timedelta`` which Skyfield interprets as TT days and seconds.
`568 <https://github.com/skyfielders/python-skyfield/issues/568>`_

* Fixed the ``.itrs_xyz`` vector of the geographic position returned
by the :meth:`~skyfield.toposlib.Geoid.subpoint_of()` method.
`673 <https://github.com/skyfielders/python-skyfield/issues/673>`_

* Skyfield now uses HTTPS instead of FTP to download JPL ephemeris files
like ``de421.bsp``. This does risk raising an error for users whose
machines have out-of-date root certificates. But it protects the
connection from outside tampering, and will keep working if the
``ssd.jpl.nasa.gov`` FTP service is ever shut down — as happened
earlier this year to FTP on NASA’s ``cddis.nasa.gov`` server.
`666 <https://github.com/skyfielders/python-skyfield/issues/666>`_

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

* Extended the :func:`~skyfield.magnitudelib.planetary_magnitude()`
routine to work with all the major planets, which upgrades it from a
prototype feature to a production feature of Skyfield.

* The :meth:`~skyfield.toposlib.Geoid.subpoint()` method has been
deprecated, because users reported that its name was a poor match for
its behavior. Four new methods have replaced it:
:meth:`~skyfield.toposlib.Geoid.latlon_of()`,
:meth:`~skyfield.toposlib.Geoid.height_of()`,
:meth:`~skyfield.toposlib.Geoid.geographic_position_of()`, and
:meth:`~skyfield.toposlib.Geoid.subpoint_of()`.
`644 <https://github.com/skyfielders/python-skyfield/issues/644>`_

* Added a timescale method :meth:`~skyfield.timelib.Timescale.linspace()`.
`617 <https://github.com/skyfielders/python-skyfield/issues/617>`_

* The :func:`~skyfield.almanac.oppositions_conjunctions()` routine,
which was originally designed only for planets, can now also handle
the Moon (which moves from opposition to conjunction much faster).

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

* The
:meth:`Angle.dstr() <skyfield.units.Angle.dstr>`
and
:meth:`Angle.hstr() <skyfield.units.Angle.hstr>`
methods now accept a ``format=`` argument
that lets callers override Skyfield’s default angle formatting
and supply their own; see `Formatting angles`.
`513 <https://github.com/skyfielders/python-skyfield/issues/513>`_

* The prototype :func:`~skyfield.magnitudelib.planetary_magnitude()`
function now works not only when given a single position, but when
given a vector of several positions.