607 lines
24 KiB
ReStructuredText
607 lines
24 KiB
ReStructuredText
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Changelog
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=========
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1.25 — 2020 July 24
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-------------------
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* Added :func:`~skyfield.data.stellarium.parse_constellations()`
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and :func:`~skyfield.data.stellarium.parse_star_names()`
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to load Stellarium star names and constellation lines.
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Constellation lines are featured in a new example script
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:ref:`neowise-chart` that produces a finder chart
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for comet C/2020 F3 NEOWISE.
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* The Hipparcos star catalog should now load faster, having switched
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behind the scenes to a higher performance Pandas import routine.
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* Fixed the ability of :meth:`~skyfield.timelib.Timescale.utc()` to
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accept a Python ``datetime.date`` object as its argument.
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`#409 <https://github.com/skyfielders/python-skyfield/issues/409>`_
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* Slightly lowered the precision of two tests when they detect that
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Python is compiled for a 32-bit processor, so the test suite can
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succeed when contributors package Skyfield for 32-bit Linux.
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`#411 <https://github.com/skyfielders/python-skyfield/issues/411>`_
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1.24 — 2020 July 20
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-------------------
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* Added methods :meth:`~skyfield.timelib.Timescale.from_datetime()` and
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:meth:`~skyfield.timelib.Timescale.from_datetimes()` to the
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:class:`~skyfield.timelib.Timescale` class, to better advertise the
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ability to build a Skyfield time from a Python ``datetime`` — an ability
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that was previously overloaded into the ``year`` parameter of the
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:meth:`~skyfield.timelib.Timescale.utc()` method (where it is still
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supported for backwards compatibility, but no longer documented).
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* Fix: improved the accuracy with which velocity is converted between
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the Earth-fixed ITRF frame that rotates with the Earth and the
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inertial GCRS frame that does not. In particular, this should make
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Earth satellite velocities more accurate.
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1.23 — 2020 July 9
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------------------
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* Added :doc:`kepler-orbits` support
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for generating the positions of comets and asteroids
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from Minor Planet Center data files.
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* Added :func:`~skyfield.positionlib.ICRF.is_behind_earth()` to
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determine whether a celestial object is blocked from an Earth
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satellite’s view by the Earth itself.
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* Replaced the awkward and hard-to-explain ``rough_period`` search
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parameter with the conceptually simpler ``step_days`` parameter, and
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updated the instructions in :doc:`searches` to match.
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* Made the :meth:`~skyfield.iokit.Loader.tle_file()` import method less
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strict about Earth satellite names: any text on the line before two
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lines of TLE data is now saved as the satellite name. A parameter
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``skip_names=True`` turns this off if, for particular TLE files, this
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leads to unwanted text being saved.
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1.22 — 2020 Jun 8
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-----------------
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* Skyfield’s improved time precision (stored internally as two floats)
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is now used in computing ephemeris positions, Earth orientation, and
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light-travel time, producing position angles which change much more
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smoothly over time on a sub-milliarcsecond scale.
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* :doc:`searches` is now documented for custom events that users define
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themselves, instead of only being documented for the official
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pre-written :doc:`almanac` functions. Not only discrete events but
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also maxima and minima are now officially supported and documented,
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thanks to a rewrite of the underlying code.
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* Time objects no longer cache the nutation and precession matrices,
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since they are never used again after being multiplied together to
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create the equinox-of-date rotation matrix. This should save 144
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bytes for each time in a :class:`~skyfield.timelib.Time` array.
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* It is now possible to :ref:`from-satrec` thanks to a new Earth
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satellite constructor method.
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`#384 <https://github.com/skyfielders/python-skyfield/issues/384>`_
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* Added :meth:`~skyfield.iokit.Loader.build_url()` that returns the URL
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from which Skyfield will download a file.
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`#382 <https://github.com/skyfielders/python-skyfield/issues/382>`_
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* Added :meth:`~skyfield.jpllib.SpiceKernel.close()` to support
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applications that need to do fine-grained resource management or whose
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testing framework check for dangling open files.
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`#374 <https://github.com/skyfielders/python-skyfield/issues/374>`_
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* Skyfield’s dependency list now asks for “jplephem” version 2.13 or
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later. Skyfield 1.21, alas, could incur a ``Module not found`` error
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when importing ``jplephem.exceptions`` if a user had an old “jplephem”
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version already installed.
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`#386 <https://github.com/skyfielders/python-skyfield/issues/386>`_
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1.21 — 2020 May 29
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------------------
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* Added :func:`~skyfield.positionlib.ICRF.is_sunlit()` to determine
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whether Earth satellites in orbit are in Earth’s shadow or not, thanks
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to a pull request from Jesse Coffey.
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* Added :func:`~skyfield.positionlib.position_of_radec()`
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to replace the poorly designed ``position_from_radec()``.
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* Skyfield :class:`~skyfield.timelib.Time` objects now have microsecond
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internal accuracy, so round trips to and from Python datetimes should
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now preserve all the microsecond digits.
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* The :meth:`~skyfield.timelib.Time.utc_strftime()` method now rounds to
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the nearest minute or second if it sees that either minutes or seconds
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are the smallest unit of time in the format string.
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* The 6 numbers in the sequence ``t.utc`` can now be accessed by the
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attribute names ``year``, ``month``, ``day``, ``hour``, ``minute``,
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and ``second``.
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* Nutation routines should now be faster and have a smaller memory
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footprint, thanks to a rewrite that uses more optimized NumPy calls.
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`#373 <https://github.com/skyfielders/python-skyfield/issues/373>`_
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* Thanks to Jérôme Deuchnord, the exception raised when asking for a
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position out-of-range of a JPL ephemeris now shows the calendar dates
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for which the ephemeris is valid and carries several useful attributes.
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`#356 <https://github.com/skyfielders/python-skyfield/pull/356>`_
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1.20 — 2020 April 24
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--------------------
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* Erik Tollerud contributed a fix for a deprecation warning about SSL
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from the most recent versions of Python (“cafile, cpath and cadefault
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are deprecated, use a custom context instead”). The file download
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routine now auto-detects which mechanism your Python supports.
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`#363 <https://github.com/skyfielders/python-skyfield/pull/363>`_
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* Added an ``elevation_m`` argument to
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:meth:`~skyfield.planetarylib.PlanetaryConstants.build_latlon_degrees()`.
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1.19 — 2020 April 23
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--------------------
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* To hopefully fix the ``SSL: CERTIFICATE_VERIFY_FAILED`` errors that
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some users encounter when downloading timescale files, Skyfield has
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taken the risk of switching away from your system’s SSL certificates
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to the certificate bundle from the ``certifi`` package.
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`#317 <https://github.com/skyfielders/python-skyfield/issues/317>`_
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* Added a new almanac routine for finding :ref:`lunar-nodes`.
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`#361 <https://github.com/skyfielders/python-skyfield/issues/361>`_
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* Gave topos objects a new :meth:`~skyfield.toposlib.Topos.itrf_xyz()`
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method that returns their raw ITRF coordinates.
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`#354 <https://github.com/skyfielders/python-skyfield/issues/354>`_
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* Fixed the sign of the velocity vector when two vectors are directly
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geometrically subtracted.
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`#355 <https://github.com/skyfielders/python-skyfield/issues/355>`_
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1.18 — 2020 March 26
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--------------------
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* Deprecated the old hybrid-key satellite dictionary returned by
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``load.tle()`` in favor of a simple list returned by the new
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:meth:`~skyfield.iokit.Loader.tle_file()` routine.
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`#345 <https://github.com/skyfielders/python-skyfield/issues/345>`_
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* The almanac :func:`~skyfield.searchlib.find_discrete()` routine no
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longer returns extraneous values in its second return value if no
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changes of state were found.
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`#339 <https://github.com/skyfielders/python-skyfield/issues/339>`_
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`#351 <https://github.com/skyfielders/python-skyfield/issues/351>`_
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* Added documentation and support for computing lunar libration.
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`#80 <https://github.com/skyfielders/python-skyfield/issues/80>`_
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1.17 — 2020 February 2
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----------------------
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* Upgraded to a new version of the ``sgp4`` Python library that, when
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possible, uses the fast official C++ implementation of SGP4.
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* Added a :meth:`~skyfield.sgp4lib.EarthSatellite.find_events()` Earth
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satellite method that finds the times at which a satellite rises,
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culminates, and sets.
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* Improved the logic behind the :doc:`almanac` routines to avoid rare
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situations in which a cluster of nearly identical times would be
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produced for what should really be considered a single event.
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`#333 <https://github.com/skyfielders/python-skyfield/issues/333>`_
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* Fixed the :meth:`~skyfield.timelib.Time.utc_strftime()` method so it
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does not report that every day in all of recorded history is a Monday.
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`#335 <https://github.com/skyfielders/python-skyfield/issues/335>`_
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1.16 — 2019 December 20
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-----------------------
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* Added basic :doc:`planetary` support, enough to compute the position
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of a given latitude and longitude on the surface of the Moon.
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`#79 <https://github.com/skyfielders/python-skyfield/issues/79>`_
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`#124 <https://github.com/skyfielders/python-skyfield/issues/124>`_
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`#258 <https://github.com/skyfielders/python-skyfield/issues/258>`_
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* Added :func:`~skyfield.almanac.oppositions_conjunctions()` for finding
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the dates when a planet is at opposition and conjunction with the sun.
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* Added :func:`~skyfield.trigonometry.position_angle_of()` for computing
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astronomical position angles.
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1.15 — 2019 November 20
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-----------------------
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* Changed the URL for the Hipparcos catalog, because the VizieR archives
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FTP server is no longer responding.
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`#301 <https://github.com/skyfielders/python-skyfield/issues/301>`_
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* Added a :func:`~skyfield.almanac.dark_twilight_day()` function that
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not only handles sunrise and sunset but also all three kinds of
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twilight.
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`#225 <https://github.com/skyfielders/python-skyfield/issues/225>`_
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1.14 — 2019 November 1
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----------------------
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* Changed the URL from which leap second files are downloaded; the
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server that previously provided them is no longer responding.
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Thanks to Richard Shaw for the pull request.
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`#296 <https://github.com/skyfielders/python-skyfield/issues/296>`_
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`#297 <https://github.com/skyfielders/python-skyfield/issues/297>`_
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* Added a :func:`~skyfield.almanac.risings_and_settings()` function for
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computing rising and setting times.
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`#271 <https://github.com/skyfielders/python-skyfield/issues/271>`_
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1.13 — 2019 October 10
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----------------------
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* Provided a constellation lookup routine through
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:func:`~skyfield.api.load_constellation_map()`.
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* Added a ``position_from_radec()`` function.
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* Fixed the ``apparent()`` method in the case where a single observer
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position is observing an entire vector of target positions.
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`#229 <https://github.com/skyfielders/python-skyfield/issues/229>`_
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1.12 — 2019 September 2
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-----------------------
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* Fix: an exception was being thrown when creating a ``Loader`` pointed
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at a Windows directory for which Python’s ``os.makedirs()`` function
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returned a spurious error.
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`#283 <https://github.com/skyfielders/python-skyfield/issues/283>`_
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* The internal ``reverse_terra()`` routine can now be given an
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``iterations=0`` argument if the caller wants geocentric latitude and
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longitude.
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1.11 — 2019 July 22
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-------------------
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* You can now call ``load.timescale(builtin=True)`` to use time scale
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files that Skyfield carries internally, instead of downloading them.
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Note that the time scale files distributed with any given version of
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Skyfield will gradually fall out of date.
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* Fix: indexing a position now returns a position with an actual velocity.
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`#241 <https://github.com/skyfielders/python-skyfield/issues/241>`_
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* Fix: the ``Star`` method ``from_dataframe()`` now correctly pulls
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stellar parallax data from the dataframe if available.
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`#266 <https://github.com/skyfielders/python-skyfield/issues/266>`_
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* Fix: :func:`~skyfield.searchlib.find_discrete()` was generating empty
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arrays of search dates, upsetting the astronomy code, if the start and
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end dates were very close together.
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`#240 <https://github.com/skyfielders/python-skyfield/issues/240>`_
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1.10 — 2019 February 2
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----------------------
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* Fix: teach Skyfield the new format of the Naval Observatory ∆T data
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file ``deltat.preds``, whose change in format caused Skyfield to start
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throwing an exception for new users.
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`#236 <https://github.com/skyfielders/python-skyfield/issues/236>`_
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1.9 — 2018 September 23
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-----------------------
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* Added :func:`~skyfield.almanac.seasons` to the :doc:`almanac` module
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that can be used to predict solstices and equinoxes.
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* Fix: the ecliptic coordinate routines no longer raise ``ValueError:
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too many values to unpack`` if they are passed a time array.
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`#207 <https://github.com/skyfielders/python-skyfield/issues/207>`_
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`#208 <https://github.com/skyfielders/python-skyfield/issues/208>`_
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1.8 — 2018 September 12
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-----------------------
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* There is now an :doc:`almanac` module can compute the times of
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sunrise, sunset, and the phases of the moon, based on the search
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algorithms announced at my recent PyBay talk “An Import Loop and a
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Fiery Reentry.”
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* Two new methods :meth:`~skyfield.positionlib.ICRF.cirs_xyz()` and
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:meth:`~skyfield.positionlib.ICRF.cirs_radec()` have been contributed
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which provide support for rotating a position into the Celestial
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Intermediate Reference System (CIRS).
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`#192 <https://github.com/skyfielders/python-skyfield/issues/192>`_
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1.7 — 2018 September 3
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----------------------
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* Skyfield now supports loading the Hipparcos star catalog as a Pandas
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dataframe, providing the user with convenient mechanisms for looking
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up a single star by HIP number or filtering the entire catalog by
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magnitude. See :doc:`stars` for details.
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* Ecliptic coordinates can now be produced for epochs other than J2000
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thanks to a new optional parameter specifying the desired epoch for
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the :meth:`~skyfield.positionlib.ICRF.ecliptic_latlon()` method.
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* A position that gives a position, velocity, and time can now be
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converted into full osculating orbital elements through the routine
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:func:`~skyfield.elementslib.osculating_elements_of()`.
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* A couple of bugs in the ``load()`` routine have been fixed.
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`#193 <https://github.com/skyfielders/python-skyfield/issues/193>`_
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`#194 <https://github.com/skyfielders/python-skyfield/issues/194>`_
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1.6 — 2018 July 25
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------------------
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* Both of the loader methods :meth:`~skyfield.iokit.Loader.open()` and
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:meth:`~skyfield.iokit.Loader.tle()` now accept not just URLs but also
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plain local file paths; they correctly re-download a remote file if
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“reload=True” is specified; and they allow specifying a different local
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“filename=” than the one at the end of the URL.
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* Earth satellite objects no longer try to instantiate a timescale object
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of their own, which often kicked off an unexpected download of the three
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files needed to build a timescale.
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* Satellite names are now correctly loaded from Space-Track TLE files.
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* The ability to create times using Julian Dates is now better advertised,
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thanks to dedicated timescale methods whose names end in ``…_jd()``.
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1.5 — 2018 July 4
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-----------------
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* The :meth:`~skyfield.positionlib.Geocentric.subpoint()` method
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now normalizes the longitude values it returns
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into the range −180° to 180°
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`#182 <https://github.com/skyfielders/python-skyfield/issues/182>`_
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and returns an actual elevation instead of zero.
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`#185 <https://github.com/skyfielders/python-skyfield/issues/185>`_
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* Earth satellites now return a real velocity vector instead of zero.
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`#187 <https://github.com/skyfielders/python-skyfield/issues/187>`_
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* Earth satellites now offer an
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:meth:`~skyfield.sgp4lib.EarthSatellite.ITRF_position_velocity_error()`
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method that returns raw ITRF coordinates for users interested in them.
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`#85 <https://github.com/skyfielders/python-skyfield/issues/85>`_
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1.4 — 2018 May 20
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-----------------
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* You can now specify the distance to an object when generating a
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position from altitude and azimuth coordinates.
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`#158 <https://github.com/skyfielders/python-skyfield/issues/158>`_
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* The dictionary of satellites returned when you read a TLE file
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now supports lookup by integer satellite ID, not just by name,
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and now knows how to parse TLE files from Space-Track.
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`#163 <https://github.com/skyfielders/python-skyfield/issues/163>`_
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`#167 <https://github.com/skyfielders/python-skyfield/issues/167>`_
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* Star coordinates can now be offered for any epoch, not just J2000.
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`#166 <https://github.com/skyfielders/python-skyfield/issues/166>`_
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* You can now create a time object given the UT1 date.
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`#91 <https://github.com/skyfielders/python-skyfield/issues/91>`_
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* Fractional Julian years are now available on ``Time`` objects as ``.J``.
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* The parameter DUT1 is now available on ``Time`` objects as ``.dut1``.
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`#176 <https://github.com/skyfielders/python-skyfield/issues/176>`_
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1.3 — 2018 April 15
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-------------------
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* Geocentric coordinates now have a
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:meth:`~skyfield.positionlib.Geocentric.subpoint()`
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method that computes the latitude and longitude
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of the point beneath that body.
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* All of the ``Timescale`` time constructor methods now accept arrays.
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* Emergency fix to stop Skyfield
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from endlessly downloading new copies of ``deltat.preds``,
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since the file has gone out of date at the USNO site.
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* Fixed ability of a :class:`~skyfield.starlib.Star`
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to be initialized with a tuple that breaks units into minutes and seconds
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(broke in version 1.2).
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* Issues fixed:
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`#170 <https://github.com/skyfielders/python-skyfield/issues/170>`_
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`#172 <https://github.com/skyfielders/python-skyfield/issues/172>`_
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1.2 — 2018 March 29
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-------------------
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* The documentation now describes
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how to create an excerpt of a large JPL ephemeris
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without downloading the entire file.
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Several Skyfield tests now run much faster
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because they use an ephemeris excerpt instead of waiting for a download.
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* For ``load_file()`` a leading ``~`` now means “your home directory”.
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* You can now initialize a velocity from kilometers per second
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with ``Velocity(km_per_s=...)``.
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* Empty time and angle objects no longer raise an exception when printed.
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(Thanks, JoshPaterson!)
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* Issues fixed:
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`#160 <https://github.com/skyfielders/python-skyfield/issues/160>`_
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`#161 <https://github.com/skyfielders/python-skyfield/issues/161>`_
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`#162 <https://github.com/skyfielders/python-skyfield/issues/162>`_
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1.1 — 2018 January 14
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---------------------
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* Positions can now be converted to AstroPy with
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:meth:`~skyfield.positionlib.ICRF.to_skycoord()`.
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* You can now provide a timescale of your own to an
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:meth:`~skyfield.sgp4lib.EarthSatellite`
|
||
instead of having it trying to load one itself.
|
||
|
||
* Downloaded files are no longer marked as executable on Windows.
|
||
|
||
* A friendly error message, rather than an obscure traceback, is now
|
||
returned if you try converting a position to alt/az coordinates but
|
||
the position was not measured from a position on the Earth’s surface.
|
||
|
||
1.0 — 2017 March 15
|
||
-------------------
|
||
|
||
* Brought the core API to maturity: replaced the narrow concept of
|
||
building a “body” from several ephemeris segments with the general
|
||
concept of a vector function that is the sum of several simpler vector
|
||
functions.
|
||
|
||
* Added support for adding and subtracting vector functions.
|
||
|
||
* Deprecated the Earth ``topos()`` method in favor of vector addition.
|
||
|
||
* Deprecated the Earth ``satellite()`` method in favor of vector addition.
|
||
|
||
* Deprecated the body ``geometry_of()`` method in favor of vector subtraction.
|
||
|
||
* Celestrak satellite files can now be opened with ``load.tle(url_or_filename)``.
|
||
|
||
0.9.1 — 2016 December 10
|
||
------------------------
|
||
|
||
* Attempted to speed up Earth satellite calculations by caching a single
|
||
time scale object instead of creating a new one each time.
|
||
|
||
* Fixed a possible divide-by-zero error when applying deflection to an
|
||
apparent position.
|
||
|
||
0.9
|
||
---
|
||
|
||
* The ``observe()`` method of an observer on the Earth’s surface now
|
||
correctly accounts for the way that the Earth’s gravity will deflect
|
||
the apparent position of objects that are not exactly overhead,
|
||
bringing Skyfield’s agreement with the Naval Observatory’s NOVAS
|
||
library to within half a milliarcsecond.
|
||
|
||
* The time method ``tt_calendar()`` method no longer raises a
|
||
``TypeError`` when its value is an array.
|
||
|
||
* Running ``repr()`` on a ``Time`` array now produces a more compact
|
||
string that only mentions the start and end of the time period.
|
||
|
||
* The ``api.load()`` call no longer attempts to animate a progress bar
|
||
if the user is running it under IDLE, which would try to accumulate
|
||
the updates as a single long line that eventually hangs the window.
|
||
|
||
0.8
|
||
---
|
||
|
||
* Added an `api` document to the project, in reverent imitation of the
|
||
`Pandas API Reference`_ that I keep open in a browser tab every time I
|
||
am using the Pandas library.
|
||
|
||
* New method `ICRF.separation_from()` computes the angular separation
|
||
between two positions.
|
||
|
||
* Fixed ``==`` between `Time` objects and other unrelated objects so
|
||
that it no longer raises an exception.
|
||
|
||
0.7
|
||
---
|
||
|
||
* Introduced the ``Timescale`` object with methods ``utc()``, ``tai()``,
|
||
``tt()``, and ``tdb()`` for building time objects, along with a
|
||
``load.timescale()`` method for building a new ``Timescale``. The
|
||
load method downloads ∆T and leap second data from official data
|
||
sources and makes sure the files are kept up to date. This replaces
|
||
all former techniques for building and specifying dates and times.
|
||
|
||
* Renamed ``JulianDate`` to ``Time`` and switched from ``jd`` to ``t``
|
||
as the typical variable used for time in the documentation.
|
||
|
||
* Deprecated timescale keyword arguments like ``utc=(…)`` for both the
|
||
``Time`` constructor and also for all methods that take time as
|
||
an argument, including ``Body.at()`` and ``Topos.at()``.
|
||
|
||
* Users who want to specify a target directory when downloading a file
|
||
will now create their own loader object, instead of having to specify
|
||
a special keyword argument for every download::
|
||
|
||
load = api.Loader('~/ephemeris-files')
|
||
load('de421.bsp')
|
||
|
||
0.6.1
|
||
-----
|
||
|
||
* Users can now supply a target ``directory`` when downloading a file::
|
||
|
||
load('de421.bsp', directory='~/ephemerides')
|
||
|
||
* Fix: removed inadvertent dependency on the Pandas library.
|
||
|
||
* Fix: ``load()`` was raising a ``PermissionError`` on Windows after a
|
||
successful download when it tried to rename the new file.
|
||
|
||
0.6
|
||
---
|
||
|
||
* Skyfield now generates its own estimate for ``delta_t`` if the user
|
||
does not supply their own ``delta_t=`` keyword when specifying a date.
|
||
This should make altitude and azimuth angles much more precise.
|
||
|
||
* The leap-second table has been updated to include 2015 July 1.
|
||
|
||
* Both ecliptic and galactic coordinates are now supported.
|
||
|
||
0.5
|
||
---
|
||
|
||
* Skyfield has dropped the 16-megabyte JPL ephemeris DE421 as an install
|
||
dependency, since users might choose another ephemeris, or might not
|
||
need one at all. You now ask for a SPICE ephemeris to be downloaded
|
||
at runtime with a call like ``planets = load('de421.bsp')``.
|
||
|
||
* Planets are no longer offered as magic attributes, but are looked up
|
||
through the square bracket operator. So instead of typing
|
||
``planets.mars`` you should now type ``planets['mars']``. You can run
|
||
``print(planets)`` to learn which bodies an ephemeris supports.
|
||
|
||
* | Ask for planet positions with ``body.at(t)`` instead of ``body(t)``.
|
||
|
||
* Per IAU 2012 Resolution B2, Skyfield now uses lowercase *au* for the
|
||
astronomical unit, and defines it as exactly 149 597 870 700 meters.
|
||
While this API change is awkward for existing users, I wanted to make
|
||
the change while Skyfield is still pre-1.0. If this breaks a program
|
||
that you already have running, please remember that a quick ``pip``
|
||
``install`` ``skyfield==0.4`` will get you up and running again until
|
||
you have time to edit your code and turn ``AU`` into ``au``.
|
||
|
||
0.4
|
||
---
|
||
|
||
* To prevent confusion, the :meth:`~skyfield.timelib.Time.astimezone()`
|
||
and :meth:`~skyfield.timelib.Time.utc_datetime()` methods
|
||
have been changed to return only a ``datetime`` object.
|
||
If you also need a leap second flag returned,
|
||
call the new methods
|
||
:meth:`~skyfield.timelib.Time.astimezone_and_leap_second()`
|
||
and :meth:`~skyfield.timelib.Time.utc_datetime_and_leap_second()`.
|
||
|
||
0.3
|
||
---
|
||
|
||
* The floating-point values of an angle
|
||
``a.radians``, ``a.degrees``, and ``a.hours``
|
||
are now attributes instead of method calls.
|
||
|
||
|
||
.. _Pandas API Reference: http://pandas.pydata.org/pandas-docs/stable/api.html
|