  petitRADTRANS (pRT) is a fast radiative transfer code used for computing
emission and transmission spectra of exoplanet atmospheres, combining a FORTRAN
back end with a Python based user interface. It is widely used in the exoplanet
community with 222 references in the literature to date, and has been
benchmarked against numerous similar tools. The spectra calculated with pRT can
be used as a forward model for fitting spectroscopic data using Monte Carlo
techniques, commonly referred to as an atmospheric retrieval. The new retrieval
module combines fast forward modelling with nested sampling codes, allowing for
atmospheric retrievals on a large range of different types of exoplanet data.
Thus it is now possible to use pRT to easily and quickly infer the atmospheric
properties of exoplanets in both transmission and thermal emission.
