Specutils

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

New Features
^^^^^^^^^^^^

- Implement ``SpectralCoord`` object. [524]

- Implement cross-correlation for finding redshift/radial velocity. [544]

- Improve FITS file identification in default_loaders. [545]

- Support ``len()`` for ``SpectrumCollection`` objects. [575]

- Improved 1D JWST loader and allow parsing into an ``SpectrumCollection`` object. [579]

- Implemented 2D and 3D data loaders for JWST products. [595]

- Include documentation on how to use dust_extinction in specutils. [594]

- Include example of spectrum shifting in docs. [600]

- Add new default excise_regions exciser function and improve subregion handling. [609]

- Implement use of ``SpectralCoord`` in ``Spectrum1D`` objects. [610]

Bug Fixes
^^^^^^^^^

- Fix stacking and unit treatment in ``SpectrumCollection.from_spectra``. [578]

- Fix spectral axis unit retrieval. [581]

- Fix bug in subspectrum fitting. [586]

- Fix uncertainty to weight conversion to match astropy assumptions. [594]

- Fix warnings and log messages from ASDF serialization tests. [597]

Other Changes and Additions
^^^^^^^^^^^^^^^^^^^^^^^^^^^

- Remove spectral_resolution stub from Spectrum1D. [606]

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

New Features
^^^^^^^^^^^^

- Make specutils compatible with Astropy 4.0 (breaking change). [462]

- Remove all wcs adapter code and rely on APE14 implementation. [462]

Bug Fixes
^^^^^^^^^

- Address ``MexicanHat1D`` name change in documentation. [564]

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

API Changes
^^^^^^^^^^^

- Resamplers now include ``extrapolation_treatment`` argument. [537]

- Template fitting now returns an array of chi squared values for each template. [551]

New Features
^^^^^^^^^^^^

- Masks now supported in fitting operations. [519]

- Resamplers now support resamping beyond the edge of a spectrum using. [537]

- New template fitting for redshift finding. [527]

- New continuum checker to discern whether continuum is normalized or subtracted. [538]

- Include documentation on how to achieve splicing using specutils. [536]

- Include function to calculate masks based on S/N thresholding. [509]

Bug Fixes
^^^^^^^^^

- Include new regions regression tests. [345]

- Fix fitting documentation code block test. [478]

- Fix Apogee loader to incorporate spectral axis keyword argument. [560]

- Fix tabular fits writer and include new regression test. [539]

- Fix dispersion attribute bug in ``Spectrum1D`` objects. [530]

- Correctly label regression tests that require remote data. [525]

Other Changes and Additions
^^^^^^^^^^^^^^^^^^^^^^^^^^^

- Switch to using ``gaussian_sigma_width`` for ``Gaussian1D`` fitting estimator. [434]

- Update documentation side bar to include page listing. [556]

- New documentation on ``spectrum_mixin``. [532]

- Model names are now preserved in the ``fit_lines`` operation. [526]

- Clearer error messages for incompatible units in line fitting. [520]

- Include travis stages in test matrix. [515]

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

New Features
^^^^^^^^^^^^

- New redshift and radial velocity storage on `Spectrum1D` object.

- Spectral template matching including resampling.

- Error propagation in convolution smoothing.

- Sub-pixel precision for fwhm calculations.

- New spectral resampling functions.

- New IRAF data loaders.

- New FWZI calculation.

Bug Fixes
^^^^^^^^^

- Stricter intiailizer for ``Spectrum1D``.

- Correct handling of weights in line fitting.

- Array size checking in `Spectrum1D` objects.

- Fix for continuum fitting on pixel-axis dispersions.

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

Bug Fixes
^^^^^^^^^

- Fix comparison of FITSWCS objects in arithmetic operations.

- Fix example documentation when run in python interpreter.

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

Bug Fixes
^^^^^^^^^

- Bugfixes for astropy helpers, pep8 syntax checking, and plotting in docs [416,417,419]

- All automatically generated ``SpectrumList`` loaders now have identifiers. [440]

- ``SpectralRange.from_center`` parameters corrected after change to SpectralRange interface. [433]

Other Changes and Additions
^^^^^^^^^^^^^^^^^^^^^^^^^^^

- Improve explanation on creating spectrum continua. [420]

- Wrap IO identifier functions to ensure they always return True or False and log any errors. [404]