Energy levels, transition frequencies and Einstein A coefficients were taken from JPL. The collisional rate coefficients are taken to be the same as for HCO+ and include energy levels up to J=30 and temperatures from 10 to 2000 K. For details on the extrapolation see Schöier et al. (2005).
We also provide a file with recent coefficients by Daniel et al (2005) which include the hyperfine structure of N2H+. The spectroscopic data for this datafile come from the CDMS catalog.