===================
This is a major new release. The highlight is really close compatibility of
the SALT2 model and fitting procedure with ``snfit``, the "official" SALT2
fitter.
- ``SALT2Source``: Internal interpolation scheme of ``SALT2Source``
updated to match ``snfit`` implementation exactly. Test suite now tests
against ``snfit`` implementation.
- ``fit_lc()``:
- Handling of model covariance updated to match that of ``snfit``: model
covariance is fixed for each fit and fit is repeated until convergence.
- New arguments ``phase_range`` and ``wave_range``. If given,
data outside this range will be discarded after an initial fit and
additional fits will be performed until convergence.
With ``phase_range=(-15., 45.)`` and ``wave_range=(3000., 7000.)``,
behavior approximates that of snfit with default arguments.
- Added support for covariance in photometric data measurements, and
this covariance is used in ``fit_lc()`` if present. Covariance
is stored as a ``'fluxcov'`` column in the table of measurements.
- Result includes two new attributes: ``data_mask``, a boolean array
indicating which rows in the input data were used in the final fit
(since multiple fits might be performed), and ``nfit``, the number
of fits performed.
- New argument ``warn`` can be set to False to turn off warnings about
dropping bands outside model wavelength range.
- ``read_lc()``:
- Added support for reading snfit-format "covmat" files into
a table of photometry::
>>> data = read_lc('filename', format='salt2', read_covmat=True)
>>> data['Fluxcov'].shape == (len(data), len(data))
True
- New keyword argument ``expand_bands``. When True, the returned band
column will contain ``Bandpass`` objects instead of strings. (Strings
converted to bandpass objects using ``sncosmo.get_bandpass()``.) This
is particularly useful for position-dependent bandpasses in the salt2
file format, such as ``megacampsf``: ``read_lc()`` reads the position from
the header and feeds the position to ``get_bandpass()`` to get a Bandpass
object for the correct position.
- Built-in bandpasses and magnitude systems: Many new built-in bandpasses
and magnitude systems.
- Configuration: The environment variable ``SNCOSMO_DATA_DIR`` can be
used to set the path to the data directory. If set, it takes
precedence over the ``data_dir`` variable in the configuration file
(``$HOME/.astropy/config/sncosmo.cfg``).