Version History

Note: SNCosmo uses Semantic Versioning for its version numbers. Specifically, this means that code written for sncosmo v1.0 will continue to work with any v1.x version. However, exact results may differ between versions in the 1.x series. (For example, due to changes in integration method.)

v1.5.1 (2017-05-12)

No new features or bugfixes. This release simply removes build dependencies to enable building conda packages on conda-forge.

v1.5.0 (2017-04-20)

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))
    • 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).

v1.4.0 (2016-11-16)

  • SFD98Map and get_ebv_from_map deprecated in favor of separate package sfdmap which has vastly improved performance (200x faster) for the typical case of scalar coordinates in ICRS frame.
  • animate_source() deprecated. This is a “fun extra” that is difficult to test and no longer seems to work.
  • Cython implementation of extinction functions has been factored out into a separate Python module called extinction, which is now a dependency.
  • Model.bandflux() and Source.bandflux() now integrate on a fixed wavelength grid of 5 angstroms regardless of the wavelength grid of the bandpass. This will result in small differences in results from previous sncosmo versions.
  • The internal (publicly undocumented) Spectrum class now acts more like Model; in particular, its bandflux() method now behaves the same way. As Spectrum backs SpectralMagSystem, this makes the integration of models and zeropoint spectra more consistent.
  • Experimental (non-public) support for aliases for bandpasses, such as 'SDSS::g' for 'sdssg'.
  • Sources now use cubic rather than quadratic spline interpolation internally.
  • Model.source_peakmag() and Model.set_source_peakmag() added as convenience functions for Model.source.peakmag() and Model.source.set_peakmag() respectively.
  • [Bugfix] Fixed missing import of math module in mcmc_lc() when using the priors keyword. [Backported to v1.3.1] [#143]

v1.3.0 (2016-06-30)

This is mostly a bugfix release, but it also drops support for Python 2.6. Python 2.7 is now the minimum supported Python version.

  • Updates for compatibility with AstroPy 1.2.

  • The registry now handles subclasses more robustly. For example, if magsys is an instance of SpectralMagSystem, the following used to fail:

    sncosmo.register(magsys, 'name')

    Now this works. [#132]

  • [Bugfix] SALT2Source had a bug under Python 3 (only) yielding drastically wrong fluxes. Python 2 was not affected. [#138]

v1.2.0 (2015-12-01)

  • [API change] Registry functions moved to the top-level namespace, as follows:

    • sncosmo.registry.register() -> sncosmo.register()
    • sncosmo.registry.register_loader() -> sncosmo.register_loader()
    • sncosmo.registry.retrieve() -> deprecated, use class-specific functions such as sncosmo.get_bandpass().

    The old import paths will still work for backwards compatibility.

  • nest_lc() now uses the nestle module under the hood. A new keyword method is available which selects different sampling methods implemented by nestle. The new methods provide potential efficiency gains.

  • The MLCS2k2 model is now available as a built-in Source, with the name 'mlcs2k2'.

  • Bandpasses from the Carnegie Supernova Project added to built-ins.

  • In realize_lcs(), a new scatter keyword makes adding noise optional.

  • [Bugfix] Fix built-in Bessell bandpass definitions, which were wrong by a term proportional to inverse wavelength. This was due to misinterpretation of the trasmission units. [backported to v1.1.1] [#111]

v1.1.0 (2015-08-12)

This is a mostly bugfix release with more solid support for Python 3.

  • Added Model.color() method.
  • Remove loglmax from result of nest_lc(), which was not officially documented or supported. Use np.max(res.logl) instead.
  • Fixed bug that caused non-reproducible behavior in nest_lc() even when numpy.random.seed() was called directly beforehand. [#102]
  • Fixed file I/O problems on Python 3 related to string encoding. [#83, #85]
  • Fixed problem with SDSS bandpasses being stored as integers internally, preventing them from being used with models with dust. [#100, #101]
  • Fixed problem where built-in source name and version strings were being dropped. [#82]
  • Minor doc fixes.

v1.0.0 (2015-02-23)

  • [API change] The API of mcmc_lc has changed significantly
    (the function was marked experimental in previous release).
  • [Deprecation] In result of fit_lc, res.cov_names changed to res.vparam_names.
  • [Deprecation] In result of nest_lc, res.param_names changed to res.vparam_names. This is for compatibility between the results of fit_lc and nest_lc. [#30]
  • [Deprecation] Deprecate flatten keyword argument in fit_lc() in favor of explicit use of flatten_result() function.
  • Many new built-in models.
  • Many new built-in bandpasses.
  • New remote data fetching system.
  • SALT2 model covariance available via Model.bandfluxcov() method and modelcov=True keyword argument passed to fit_lc.
  • New simulation function, zdist, generates a distribution of redshifts given a volumetric rate function and cosmology.
  • New simulation function, realize_lcs, simulates light curve data given a model, parameters, and observations.
  • Add color-related keyword arguments to plot_lc().
  • Add tighten_ylim keyword argument to plot_lc().
  • Add chisq() function and use internally in fit_lc().
  • Add SFD98Map class for dealing with SFD (1998) dust maps persistently so that the underlying FITS files are opened only once.
  • Update get_ebv_from_map() to work with new SkyCoord class in astropy.coordinates available in astropy v0.3 onward. Previously, this function did not work with astropy v0.4.x (where older coordinates classes had been removed).
  • Update to new configuration system available in astropy v0.4 onward. This makes this release incompatible with astropy versions less than 0.4.
  • Now compatible with Python 3.
  • Increased test coverage.
  • Numerous minor bugfixes.

v0.4.0 (2014-03-26)

This is non-backwards-compatible release, due to changes in the way models are defined. These changes were made after feedback on the initial design.

The most major change is a new central class Model used throughout the pacakge. A Model instance encompasses a Source and zero or more PropagationEffect instances. This is so that different source models (e.g., SALT2 or spectral time series models) can be combined with arbitrary dust models. The best way to think about this is Source and PropagationEffect define the rest-frame behavior of a SN and dust, and a Model puts these together to determine the observer-frame behavior.

  • New classes:
    • sncosmo.Model: new main container class
    • sncosmo.Source: replaces existing Model
    • sncosmo.TimeSeriesSource: replaces existing TimeSeriesModel
    • sncosmo.StretchSource: replaces existing StretchModel
    • sncosmo.SALT2Source: replaces existing SALT2Model
    • sncosmo.PropagationEffect
    • sncosmo.CCM89Dust
    • sncosmo.OD94Dust
    • sncosmo.F99Dust
  • New public functions:
    • sncosmo.read_griddata_ascii: Read file with phase wave flux rows
    • sncosmo.read_griddata_fits
    • sncosmo.write_griddata_fits
    • sncosmo.nest_lc: Nested sampling parameter estimation of SN model
    • sncosmo.simulate_vol (EXPERIMENTAL): simulation convenience function.
  • Built-ins:
    • updated SALT2 model URLs
    • added SALT2 version 2.4 (Betoule et al 2014)
  • Improvements to sncosmo.plot_lc: flexibility and layout
  • Many bugfixes

v0.3.0 (2013-11-07)

This is a release with mostly bugfixes but a few new features, designed to be backwards compatible with v0.2.0 ahead of API changes coming in the next version.

  • New Functions:

    • sncosmo.get_ebv_from_map: E(B-V) at given coordinates from SFD map.
    • sncosmo.read_snana_ascii: Read SNANA ascii format files.
    • sncosmo.read_snana_fits: Read SNANA FITS format files.
    • sncosmo.read_snana_simlib: Read SNANA ascii “SIMLIB” files.
  • registry is now case-independent. All of the following now work:

  • Photometric data can be unordered in time. Internally, the data are sorted before being used in fitting and typing.

  • Numerous bugfixes.

v0.2.0 (2013-08-20)

  • Added SN 2011fe Nearby Supernova Factory data to built-in models as '2011fe'

  • Previously “experimental” functions now included:

    • sncosmo.fit_lc (previously sncosmo.fit_model)
    • sncosmo.read_lc (previously sncosmo.readlc)
    • sncosmo.write_lc (previously sncosmo.writelc)
    • sncosmo.plot_lc (previously sncosmo.plotlc)
  • New functions:

    • sncosmo.load_example_data: Example photometric data.
    • sncosmo.mcmc_lc: Markov Chain Monte Carlo parameter estimation.
    • sncosmo.animate_model: Model animation using matplotlib.animation.
  • Fitting: sncosmo.fit_lc now uses the iminuit package for minimization by default. This requires the iminuit package to be installed, but the old minimizer (from scipy) can still be used by setting the keyword method='l-bfgs-b'.

  • Plotting: Ability to plot model synthetic photometry without observed data, using the syntax:

    >>> sncosmo.plot_lc(model=model, bands=['band1', 'band2'])
  • Photometric data format: Photometric data format is now more flexible, allowing various names for table columns.

v0.1.0 (2013-07-15)

Initial release.