Observed transitions of H₂CS and its isotopologues towards TMC-1. The abscissa corresponds to the local standard of rest velocity of the lines adopting the rest frequencies given in Table B.1, except for the bottom panel (H₂C³³S) for which it corresponds to the rest frequency. The ordinate corresponds to the antenna temperature corrected for atmospheric and telescope losses in mK. The derived line parameters are given in Table B.1. The synthetic spectra (red line) are derived from the LVG model described in Section 4.5. The modelled spectra for the 3₁₃−2₁₂ transition of H₂CS, H₂C³⁴S and H₂¹³CS have been multiplied by a correction factor indicated in blue at the top right side of the corresponding panels. For all the other transitions, no correction factors are applied. This factor results from the adopted collisional rate coefficients for H₂CS (see Section 4.5).