Comparison between the C₂ and C₃ measurements. Each point represents a velocity component for which both molecules are detected. Upper panel: The velocity offsets of C₂ and C₃ (relative to the barycentric frame) are well aligned, suggesting the two molecules are detected in the same velocity component. Lower panel: N(C₂) and N(C₃) have a good correlation, with r = 0.93. The dashed blue line represents the best linear fit from orthogonal distance regression. The 1σ confidence interval of the fit is shown as the shadow. The red triangles represent the 3σ upper limits of N(C₃) in velocity components without C₃ detection. These upper limits are not considered in the linear regression.