Skyfield

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

* There is now an :doc:`almanac` module that can compute the times of
sunrise, sunset, and the phases of the moon, based on the search
algorithms announced at my recent PyBay talk “An Import Loop and a
Fiery Reentry.”

* Two new methods :meth:`~skyfield.positionlib.ICRF.cirs_xyz()` and
:meth:`~skyfield.positionlib.ICRF.cirs_radec()` have been contributed
which provide support for rotating a position into the Celestial
Intermediate Reference System (CIRS).
`192 <https://github.com/skyfielders/python-skyfield/issues/192>`_

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

* Skyfield now supports loading the Hipparcos star catalog as a Pandas
dataframe, providing the user with convenient mechanisms for looking
up a single star by HIP number or filtering the entire catalog by
magnitude. See :doc:`stars` for details.

* Ecliptic coordinates can now be produced for epochs other than J2000
thanks to a new optional parameter specifying the desired epoch for
the ``ecliptic_latlon()`` method.

* A position that gives a position, velocity, and time can now be
converted into full osculating orbital elements through the routine
:func:`~skyfield.elementslib.osculating_elements_of()`.

* A couple of bugs in the ``load()`` routine have been fixed.
`193 <https://github.com/skyfielders/python-skyfield/issues/193>`_
`194 <https://github.com/skyfielders/python-skyfield/issues/194>`_

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

* Both of the loader methods :meth:`~skyfield.iokit.Loader.open()` and
``tle()`` now accept not just URLs but also plain local file paths;
they correctly re-download a remote file if “reload=True” is
specified; and they allow specifying a different local “filename=”
than the one at the end of the URL.

* Earth satellite objects no longer try to instantiate a timescale object
of their own, which often kicked off an unexpected download of the three
files needed to build a timescale.

* Satellite names are now correctly loaded from Space-Track TLE files.

* The ability to create times using Julian Dates is now better advertised,
thanks to dedicated timescale methods whose names end in ``…_jd()``.

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

* The :meth:`~skyfield.positionlib.Geocentric.subpoint()` method
now normalizes the longitude values it returns
into the range −180° to 180°
`182 <https://github.com/skyfielders/python-skyfield/issues/182>`_
and returns an actual elevation instead of zero.
`185 <https://github.com/skyfielders/python-skyfield/issues/185>`_

* Earth satellites now return a real velocity vector instead of zero.
`187 <https://github.com/skyfielders/python-skyfield/issues/187>`_

* Earth satellites now offer an
:meth:`~skyfield.sgp4lib.EarthSatellite.ITRF_position_velocity_error()`
method that returns raw ITRF coordinates for users interested in them.
`85 <https://github.com/skyfielders/python-skyfield/issues/85>`_

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

* You can now specify the distance to an object when generating a
position from altitude and azimuth coordinates.
`158 <https://github.com/skyfielders/python-skyfield/issues/158>`_

* The dictionary of satellites returned when you read a TLE file
now supports lookup by integer satellite ID, not just by name,
and now knows how to parse TLE files from Space-Track.
`163 <https://github.com/skyfielders/python-skyfield/issues/163>`_
`167 <https://github.com/skyfielders/python-skyfield/issues/167>`_

* Star coordinates can now be offered for any epoch, not just J2000.
`166 <https://github.com/skyfielders/python-skyfield/issues/166>`_

* You can now create a time object given the UT1 date.
`91 <https://github.com/skyfielders/python-skyfield/issues/91>`_

* Fractional Julian years are now available on ``Time`` objects as ``.J``.

* The parameter DUT1 is now available on ``Time`` objects as ``.dut1``.
`176 <https://github.com/skyfielders/python-skyfield/issues/176>`_

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

* Geocentric coordinates now have a
:meth:`~skyfield.positionlib.Geocentric.subpoint()`
method that computes the latitude and longitude
of the point beneath that body.

* All of the ``Timescale`` time constructor methods now accept arrays.

* Emergency fix to stop Skyfield
from endlessly downloading new copies of ``deltat.preds``,
since the file has gone out of date at the USNO site.

* Fixed ability of a :class:`~skyfield.starlib.Star`
to be initialized with a tuple that breaks units into minutes and seconds
(broke in version 1.2).

* Issues fixed:
`170 <https://github.com/skyfielders/python-skyfield/issues/170>`_
`172 <https://github.com/skyfielders/python-skyfield/issues/172>`_