Wikipedia
HITRAN - HITRAN (an acronym for High Resolution Transmission) is a compilation of spectroscopic parameters that a variety of computer codes use to predict and simulate the transmission and emission of light in gaseous media including the atmosphere, laboratory cells, etc. The original version was compiled by the Air Force Cambridge Research Laboratories (1960s). HITRAN is maintained and developed at the Harvard-Smithsonian Center for Astrophysics, Cambridge MA, USA.
HITRAN is the worldwide standard for calculating or simulating atmospheric molecular transmission and radiance from the microwave through ultraviolet region of the spectrum. The current version contains 47 molecular species along with their most significant isotopologues. These data are archived as a multitude of high-resolution line transitions, each containing many spectral parameters required for high-resolution simulations. In addition there are about 50 molecular species collected as cross-section data. These latter include anthropogenic constituents in the atmosphere such as the chlorofluorocarbons.
An online tool for browsing, filtering, and plotting the data, called HITRANonline, is provided. The HITRAN database can also be downloaded in its entirety from an FTP site at the Harvard–Smithsonian Center for Astrophysics. There is no charge for downloading the database.