Ligo.skymap

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

- Add support for the ``--detector-disabled`` command line option to the
``bayestar-localize-coincs`` tool, for consistency with
``bayestar-localize-lvalert`` tool.

- Remove installation dependency on astroquery, because it is only needed for
the unit tests.

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

- Add a monkey patch to work around a regression in Astropy 3.2 that broke
WCS transformations from ITRS to ICRS coordinates.
See https://github.com/astropy/astropy/pull/9609.

- Fix a bug in the Python C extension code that could cause out-of-memory
errors to be misreported as a SystemError with the message ``<built-in
function rasterize> returned NULL without setting an error``, instead of as a
MemoryError.

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

- The ``bayestar-inject`` script now assumes that the source distribution is
specified per unit comoving volume per unit proper time, rather than per unit
comoving volume per unit observer time. This is in agreement with the
conventional definition for LIGO/Virgo astrophysical rates.

- The ``bayestar-inject`` and ``ligo-skymap-from-samples`` scripts now accept
an optional integer value for the ``-j`` flag to set the number of
subprocesses.

- ``ligo-skymap-from-samples`` will use all posterior samples if the value of
the ``--maxpts`` argument is greater than or equal to the number of posterior
samples.

- If the ``billiard`` package is present, then use it instead of the
``multiprocessing`` standard library module to parallelize
``ligo-skymap-from-samples`` so that the script's Python entry point can
be called from daemon processes (for example, inside Celery tasks).

- Switch from WMAP9 to Planck15 cosmological parameters.

- ``ligo.skymap.kde.Clustered2DSkyKDE.as_healpix()`` has an optional
``top_nside`` to allow for better initial grid, before refinement.
``ligo-skymap-from-samples`` has an additional ``--top-nside`` argument,
accordingly.

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

- Build macOS wheels with OpenMP.

- Record the command line with which ``ligo-skymap-stats`` was called by
writing it to the ASCII table output as a comment line starting with `.

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

- Fix a regression that caused ``ligo-skymap-flatten`` to fail for 2D sky maps.

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

- Add installation instructions for both pip and conda.

- Introduce the :mod:`ligo.skymap.postprocess.crossmatch` module for fast
cross-matching of sky maps with galaxy redshift catalogs.

This module used to be named :mod:`ligo.skymap.postprocess.find_injection`
because it was originally designed for recovering injections (simulated
signals) from sky localization simulations. We changed the name because
galaxy cross matching is probably a more common use case than injection
finding.

The :func:`~ligo.skymap.postprocess.crossmatch.crossmatch` method also got
some performance improvements for cross matching of large numbers of targets.
Previously, to process :math:`n` targets, it took about :math:`(4 + 0.008 n)`
seconds --- for a catalog of 300k targets, about 40 minutes. Now, it takes
about 4 seconds total regardless of the number of targets.

Note that the :mod:`ligo.skymap.postprocess.crossmatch` API is likely to
change as documentation for it improves.

- Several performance improvements for BAYESTAR:

- Add GCC branch prediction hints.

- Exploit nested parallelism in radial integrator lookup table generation.

- Calculate signal amplitudes using single-precision floating point.

- Add tracepoints for Intel's Instrumentation and Tracing Technology (ITT)
API, which can be enabled at build time by passing the ``--with-ittnotify``
option to ``python setup.py build``.