Astropy

===========================

Bug Fixes
---------

astropy.io.fits
^^^^^^^^^^^^^^^

- Fix ``Header.update`` which was dropping the comments when passed
a ``Header`` object. [8840]

astropy.modeling
^^^^^^^^^^^^^^^^

- ``Moffat1D.fwhm`` and ``Moffat2D.fwhm`` will return a positive value when
``gamma`` is negative. [8801, 8815]

astropy.units
^^^^^^^^^^^^^

- Fixed a bug that prevented ``EarthLocation`` from being initialized with
numpy >=1.17. [8849]

astropy.visualization
^^^^^^^^^^^^^^^^^^^^^

- Fixed ``quantity_support`` to work around the fact that matplotlib
does not detect subclasses in its ``units`` framework. With this,
``Angle`` and other subclasses work correctly. [8818]

- Fixed ``quantity_support`` to work properly if multiple context managers
are nested. [8844]

===========================

Bug Fixes
---------

astropy.io.fits
^^^^^^^^^^^^^^^
- Fixed bug in ``ColDefs._init_from_array()`` that caused unsigned datatypes
with the opposite endianness as the host architecture to fail the
TestColumnFunctions.test_coldefs_init_from_array unit test. [8460]

astropy.io.misc
^^^^^^^^^^^^^^^

- Explicitly set PyYAML default flow style to None to ensure consistent
astropy YAML output for PyYAML version 5.1 and later. [8500]

astropy.io.votable
^^^^^^^^^^^^^^^^^^

- Block floating-point columns from using repr format when converted to Table
[8358]

astropy.stats
^^^^^^^^^^^^^

- Fixed issue in ``bayesian_blocks`` when called with the ``ncp_prior``
keyword. [8339]

astropy.units
^^^^^^^^^^^^^

- Fix ``take`` when one gets only a single element from a ``Quantity``,
ensuring it returns a ``Quantity`` rather than a scalar. [8617]

===========================

New Features
------------

astropy.utils
^^^^^^^^^^^^^

- The ``deprecated_renamed_argument`` decorator now capable deprecating an
argument without renaming it. It also got a new ``alternative`` keyword
argument to suggest alternative functionality instead of the removed
one. [8324]


Bug Fixes
---------

astropy.io.fits
^^^^^^^^^^^^^^^

- Fixed bug in ``ColDefs._init_from_array()`` that caused non-scalar unsigned
entries to not have the correct bzero value set. [8353]

astropy.modeling
^^^^^^^^^^^^^^^^

- Fixed compatibility of ``JointFitter`` with the latest version of Numpy.
[7984]

astropy.table
^^^^^^^^^^^^^

- Fix ``.quantity`` property of ``Column`` class for function-units (e.g.,
``dex``). Previously setting this was possible, but getting raised
an error. [8425]

- Fixes a bug where initializing a new ``Table`` from the final row of an
existing ``Table`` failed. This happened when that row was generated using
the item index ``[-1]``. [8422]

astropy.wcs
^^^^^^^^^^^

- Fix bug that caused ``WCS.has_celestial``, ``wcs_to_celestial_frame``, and
other functionality depending on it to fail in the presence of correlated
celestial and other axes. [8420]


Other Changes and Additions
---------------------------

- Fixed ``make clean`` for the documentation on Windows to ensure it
properly removes the ``api`` and ``generated`` directories. [8346]

- Updating bundled ``pytest-openfiles`` to v0.3.2. [8434]

- Making ``ErfaWarning`` and ``ErfaError`` available via
``astropy.utils.exceptions``. [8441]

===========================

Bug Fixes
---------

astropy.io.ascii
^^^^^^^^^^^^^^^^

- Fix fast reader C tokenizer to handle double quotes in quoted field.
[8283]

astropy.io.fits
^^^^^^^^^^^^^^^

- Fix a bug in ``io.fits`` with writing Fortran-ordered arrays to file
objects. [8282]

astropy.units
^^^^^^^^^^^^^

- Add support for ``np.matmul`` as a ``ufunc`` (new in numpy 1.16).
[8264, 8305]

astropy.utils
^^^^^^^^^^^^^

- Fix failures caused by IERS_A_URL being unavailable by introducing
IERS_A_URL_MIRROR. [8308]

===========================

Bug Fixes
---------

astropy.convolution
^^^^^^^^^^^^^^^^^^^

- Fix Moffat2DKernel's FWHM computation, which has an influence on the default
size of the kernel when no size is given. [8105]

astropy.coordinates
^^^^^^^^^^^^^^^^^^^

- Disable ``of_address`` usage due to Google API now requiring API key. [7993]

astropy.io.fits
^^^^^^^^^^^^^^^

- ``fits.append`` now correctly handles file objects with valid modes other
than ``ostream``. [7856]

astropy.table
^^^^^^^^^^^^^

- Fix ``Table.show_in_notebook`` failure when mixin columns are present. [8069]

astropy.tests
^^^^^^^^^^^^^

- Explicitly disallow incompatible versions of ``pytest`` when using the test
runner. [8188]

astropy.units
^^^^^^^^^^^^^

- Fixed the spelling of the 'luminous emittance/illuminance' physical
property. [7942]

astropy.visualization
^^^^^^^^^^^^^^^^^^^^^

- Fixed a bug that caused origin to be incorrect if not specified. [7927]

- Fixed a bug that caused an error when plotting grids multiple times
with grid_type='contours'. [7927]

- Put an upper limit on the number of bins in ``hist`` and ``histogram`` and
factor out calculation of bin edges into public function
``calculate_bin_edges``. [7991]


Other Changes and Additions
---------------------------

- Fixing ``astropy.__citation__`` to provide the full bibtex entry of the 2018
paper. [8110]

- Pytest 4.0 is not supported by the 2.0.x LTS releases. [8173]

- Updating bundled ``pytest-remotedata`` to v0.3.1. [8174]

- Updating bundled ``pytest-doctestplus`` to v0.2.0. [8175]

- Updating bundled ``pytest-openfiles`` to v0.3.0. [8176]

- Adding ``warning_type`` keyword argument to the "deprecated" decorators to
allow issuing custom warning types instead of the default
``AstropyDeprecationWarning``. [8178]

==========================

Bug Fixes
---------

astropy.io.ascii
^^^^^^^^^^^^^^^^

- Fix reading of big files with the fast reader. [7885]

astropy.io.fits
^^^^^^^^^^^^^^^

- ``HDUList.__contains__()`` now works with ``HDU`` arguments. That is,
``hdulist[0] in hdulist`` now works as expected. [7282]

- ``HDUList`` s can now be written to streams in Python 3 [7850]

astropy.nddata
^^^^^^^^^^^^^^

- Fixed the bug in CCData.read when the HDU is not specified and the first one
is empty so the function searches for the first HDU with data which may not
have an image extension. [7739]

astropy.stats
^^^^^^^^^^^^^

- Fixed bugs in biweight statistics functions where a constant data
array (or if using the axis keyword, constant along an axis) would
return NaN. [7737]

astropy.table
^^^^^^^^^^^^^

- Fixed a bug in ``to_pandas()`` where integer type masked columns were always
getting converted to float. This could cause loss of precision. Now this only
occurs if there are actually masked data values, in which case ``pandas``
does require the values to be float so that ``NaN`` can be used to mark the
masked values. [7741, 7747]

astropy.tests
^^^^^^^^^^^^^

- Change the name of the configuration variable controlling the location of the
Astropy cache in the Pytest plugin from ``cache_dir`` to
``astropy_cache_dir``. The command line flag also changed to
``--astropy-cache-dir``. This prevents a conflict with the ``cache_dir``
variable provided by pytest itself. Also made similar change to
``config_dir`` option as a precaution. [7721]

astropy.units
^^^^^^^^^^^^^

- ``UnrecognizedUnit`` instances can now be compared to any other object
without raising `TypeError`. [7606]

astropy.visualization
^^^^^^^^^^^^^^^^^^^^^

- Fix compatibility with Matplotlib 3.0. [7839]

- Fix an issue that caused a crash when using WCSAxes with a custom Transform
object and when using ``grid_type='contours'`` to plot a grid. [7846]

astropy.wcs
^^^^^^^^^^^

- Instead of raising an error ``astropy.wcs`` now returns the input when
the input has zero size. [7746]

- Fix ``malloc(0)`` bug in ``pipeline_all_pixel2world()`` and
``pipeline_pix2foc()``. They now raise an exception for input with
zero coordinates, i.e. shape = (0, n). [7806]

- Fixed an issue with scalar input when WCS.naxis is one. [7858]

Other Changes and Additions
---------------------------

- Added a new ``astropy.__citation__`` attribute which gives a citation
for Astropy in bibtex format. Made sure that both this and
``astropy.__bibtex__`` works outside the source environment, too. [7718]