PyExoCross: a Python program for generating spectra and cross sections from molecular line lists

PyExoCross is a Python adaptation of the ExoCross Fortran application (Yurchenko, A&A, 614, A131 (2018)). PyExoCross is designed for postprocessing the huge molecular line lists generated by the ExoMol project and other similar initiatives such as the HITRAN and HITEMP databases. PyExoCross generates absorption and emission stick spectra, cross sections and other properties (partition functions, specific heats, cooling functions, lifetimes and oscillator strengths) based on molecular line lists. PyExoCross calculates cross sections with four line profiles: Doppler, Gaussian, Lorentzian and Voigt profiles in both sampling and binned methods; a number of options are available for computing Voigt profiles which we test for speed and accuracy. PyExoCross supports importing and exporting line lists in the ExoMol and HITRAN/HITEMP formats. PyExoCross also provides conversion between the ExoMol and HITRAN data format. In addition, PyExoCross has extra code for users to automate the batch download of line list files from the ExoMol database.