ExoTiC-LD is a python package for calculating stellar limb-darkening coefficients for specific instruments, stars, and wavelength ranges.

Stellar intensity (\(I\)) is modelled, as a function of radial position on the stellar disc (\(\mu\)), from pre-computed grids of models spanning a range of metallicity, effective temperature, and surface gravity. These intensities are combined with an instrument’s throughput and integrated over a specified wavelength range, resulting in a one-dimensional profile, \(I(\mu)\). Limb-darkening coefficients are then calculated by fitting one of the various functional forms, as outlined in Claret (2000) and Sing (2010), to the modelled \(I(\mu)\) profile.


The present version of ExoTiC-LD is built by David Grant and Hannah Wakeford.

The original IDL code was translated into python by Matthew Hill with improvements by Iva Laginja. The git history associated with the original implementation can be found in the ExoTiC-ISM package from which this is a spin-off repository. We also thank Natasha Batalha for providing the JWST throughput information from their PandExo package and to Lili Alderson for reviewing and testing.

If you make use of ExoTiC-LD in your research, see the citation page for info on how to cite this package and the underlying stellar models.

You can find other software from the Exoplanet Timeseries Characterisation (ExoTiC) ecosystem over on GitHub.