Energy levels, transition frequencies and Einstein A coefficients were taken from JPL for pure rotational lines. Vibration-rotation transition frequencies from Goddon et al. (1991). A-values computed from the transition dipole moments and fit to the Herman-Wallis factors of Pine et al. (1985). The values are similar (but not identical) to the values in HITRAN 2004.

Collisional rate coefficients with He are from Reese et al (2005). Electron impact rates were calculated in the Born approximation, scaled to the R-matrix calculations by Thummel et al (1992). Rates with ortho and para H₂ are from Guillon & Stoecklin (2012). For a detailed description see Van der Tak et al (2012).