Observed data of Orion KL, Sgr B2, B1-1, and TMC-1 taken with the IRAM 30 m telescope (histogram black spectra), together with the synthetic spectra of gauche-CH₃CH₂SCH₃ (red thin curve) and trans-CH₃CH₂SCH₃ (blue thin curve) obtained using MADEX and the physical parameters shown in Table 4. The synthetic total model for the 30 m data of Orion KL (see Cernicharo et al. 2016) and Sgr B2(N) (see Belloche et al. 2013) is overlaid in green. Radial velocities (v_LSR) of +9.0 km s⁻¹, +64.0 km s⁻¹, +6.7 km s⁻¹, and +6.0 km s⁻¹ are assumed for Orion KL, Sgr B2, B1-b, and TMC-1, respectively.