bytran is an application for calculating atmospheric and molecular absorption spectra using the HITRAN database and the line-by-line method. The concentrations of molecules, pathlength, atmospheric pressure, temperature, and other input parameters are used to model the gas mixture optical transmission spectra as a function of wavelength.

Additional information is available at the bytran website and in the following publication, http://dx.doi.org/10.1007/s12145-017-0288-4 (a view only version of this publication is available at http://rdcu.be/piDB).