Rotational diagram analysis of H₂CO and c-C₃H₂. First row: disk-averaged rotational diagram analysis applied to the two lines of the H₂CO and c-C₃H₂ molecules, respectively. The average excitation temperatures and column densities are indicated on the top of the two panels. The dashed lines correspond to the best fit results for N_t and T_ex, while the solid lines are 100 random results from the posterior distribution of the emcee fit. Bottom row: radial profiles of the total column density (left panel) and of the excitation temperature (right panel) from H₂CO rotational diagram analysis, applied to $0_{\cdot }^{\mathrm{\prime }\mathrm{\prime }}1$ wide annuli. The solid lines show the median of the posterior distribution (which is representative of the best fit as the posterior distribution is well described by a Gaussian) from the emcee fit, for N_t and T_ex, while the ribbons represent the 16th and 84th percentiles. The horizontal dark blue line shows the results from the disk-average rotational diagram (from top left panel). Gray regions mark the radial range of the expected location of the CO snowline (Law et al. 2024).