Ligo.skymap

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

- Update installation instructions to state that installation with pip requires
pip 19.3 or newer. This has been the case since ligo.skymap 0.1.16.

- Teach BAYESTAR to respect the ``f_final`` column in the ``sngl_inspiral``
table for pre-merger, early warning templates.

- Ensure that BAYESTAR's arrival time prior is long enough to contain at least
half a cycle of the template autocorrelation sequence. Previously, the
duration of the arrival time prior was calculated solely from the light
travel times between the participating detectors. This fixes an issue where
SNR time series for early-warning events could have been cropped to only 1-3
samples.

- Change BAYESTAR's strategy for evaluating SNR time series from Catmull-Rom
interpolation of the real and imaginary parts to Catmull-Rom interpolation of
the amplitude and phase. The old interpolation method could produce
oscillatory artifacts in the SNR amplitude if the data are nearly critically
sampled, as is the case for early-warning BNS events. The new interpolation
method is immune to this kind of artifact, and also has much faster
convergence as a function of sample rate.

- Lift the code to apply time shifts to SNR series outside of BAYESTAR's inner
loop because there are no data dependencies on the variables of integration.
This is seen to speed up BAYESTAR by 30%.

- Add software version and command line arguments metadata to the output of
``ligo-skymap-plot-stats``.

- Fix a bug in the Lanczos sub-sample arrival time interpolant: the Lanczos
kernel should be zero for ``abs(t) >= a``.

- Remove ``requirements.txt`` file and list dependencies in ``setup.cfg``
instead.

- The ``bayestar-localize-coincs`` will no longer create HTCondor user log
files because the large number of open log files could strain the filesystem
if submitting from an NFS mount. This should reduce issues with held jobs on
certain LIGO Data Grid clusters.

- Fix deprecation warning in ``ligo-skymap-stats``.

- Remove the deprecated ``ligo.skymap.postprocess.find_injection_moc`` method,
which has been renamed to ``ligo.skymap.postprocess.crossmatch``.

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

- Update the compiler version that is used to build Linux wheels to icc
19.1.0.166 from Intel Parallel Studio XE 2020u0. Due to C ABI requirements,
the wheels are now built for the `manylinux2014
<https://www.python.org/dev/peps/pep-0599/>`_ standard.

- Fix a unit test failure with astropy < 4.0.0.

- Add support for all combinations of map projection options, including
``geo degrees globe`` and ``geo degrees zoom``. Also, ``astro`` by itself is
shorthand for ``astro hours``, and ``geo`` by itself is short for
``geo degrees``.

- ``ligo-skymap-plot`` now supports a variety of projections using the
``--projection`` option.

- Turn on continuous integration testing for Python 3.8.

- Change the license for the project as a whole to GPL 3.0 or later (GPLv3+).
Previously, the source files had been a mix of GPLv2+ and GPLv3+.

- Add ``ligo-skymap-contour-moc`` command line to create a credible region
in a MOC (Multi Order Coverage) data structure. The input can be either a
multiresolution or a flattened HEALPix probability map.

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

- 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 `.