SpectralRadex runs RADEX (ascl:1010.075) directly from Python and creates model spectra from RADEX outputs. The package uses F2PY (Fortran to Python interface generator) to compile a version of RADEX written in modern Fortran, most importantly dropping the use of common blocks. As a result, running a RADEX model creates no subprocesses and can be parallelized. SpectralRadex uses the RADEX calculated line opacities and excitation temperatures to calculate the brightness temperature as a function of frequency. This allows observed spectra to be modeled in Python in a non-LTE fashion.
https://ui.adsabs.harvard.edu/abs/2007A%26A...468..627V , https://ui.adsabs.harvard.edu/abs/2021A%26A...654A..55H ; please see additional citation information here: https://spectralradex.readthedocs.io/en/latest/user/referencing.html