Retrievals of Cassini/VIMS occultation of Titan. Top left: observations and best-fit TAUREX retrievals. Bottom left: breakdown of the extinction contributions in the tholin + CH_4(l) (HITRAN) case. Right: atmospheric properties inferred for the tholin + CH_4(l) (HITRAN) case. The source for the opacity data (i.e., HITRAN or ExoMol) is important and can slightly change the best-fit spectrum and retrieval interpretation. Overall, the Cassini data is dominated by molecular absorption from CH₄, CO, C₂H₆, and C₃H₈, as well as from extinction by hydrocarbon aerosols (tholins + CH_4(l)). The shape of the 3.4 μm absorption feature is likely best explained by the contribution of multiple species including some contribution from tholins. Overall, retrieval interpretations of Titan’s atmosphere are compatible with stratospheric inferences from previous studies (see Figure B.1).