Energy levels, transition frequencies and Einstein A coefficients were taken from CDMS and JPL (However, see notes in the case of ¹³CO). The collisional rate coefficients are adopted from Yang et al. (2010) and includes energy levels up to J=40 for temperatures ranging from 2 K to 3000 K. These rate coefficients, for collisions with both para- and ortho-H₂, use close-coupling and coupled-states approximation scattering calculations and the interaction potential of Jankowski and Szalewicz (2005).