spectra do exist for other specialized applications, such as the EM2C database for combustion applications [@12RiSoxx] or one due to Parigger [[*et al*]{}]{} for studies of laser-induced plasmas [@15PaWoSu].

Planets and cool stars share some common fundamental characteristics: they are faint, their radiation peaks in the infrared and their atmosphere is dominated by strong molecular absorbers. Modelling planetary and stellar atmospheres is therefore difficult as their spectra are extremely rich in structure with hundreds of thousands to many billions of spectral lines which may be broadened by high-pressure and temperature effects.

The ExoMol project [@jt528] aims to provide the molecular line lists that astronomers need in order to understand the physics and chemistry of astronomical bodies cool enough to form molecules in their atmospheres. In particular for extrasolar planets, brown dwarfs and cool stars [@jt143; @aha97; @13TiEnCo.exo], as well as circumstellar structures such as planetary envelopes and molspheres [@08Tsuji]. In practice these data are also useful for a wide range of other scientific disciplines; examples include studies of the Earth’s atmosphere [@14ScGaHe; @15LaPoTs], hypersonic non-equilibrium [@15LoSuBo], analysis of laboratory spectra [@14FoGoHe; @jt616; @16NiReTaKa.CH4], measurements of hot reactive gases [@13GrFaNi] and the proposed remote analysis of molecular composition using laser oblation 