Comparisons between models with and without C₂H₄, and the resulting retrieved values for methane and T_eq for the Eureka1 reductions. The significance noted is derived from the Bayesian evidence of each model. The presence of C₂H₄ drives the T_eq further down from the expected T_eq. We find a slight constraint on C₂H₄ at VMR abundances of ∼10^−6.20 and a slightly lower ﹩{\chi }_{\nu }^{2}﹩ value of 1.71 in comparison to our model without C₂H₄ (﹩{\chi }_{\nu }^{2}﹩ = 1.73). We note the evidence for this feature is more significant in visit 2 than visit 1. For reference, Figure J2 shows the individual spectral contribution of C₂H₄ to the model shown above, and the arrow in the plot above highlights the region of strongest contribution from C₂H₄.