CH₃CCH synthetic spectra (in red for cores #10 and #11, in black for the others) overlaid on the observed spectra. The parameters used for the synthetic spectra are listed in Table 2. The CH₃CCH lines are contaminated by an ethanol line at 102.534 GHz in cores #1, #2, #3, and #4, an ethylene glycol line at 102.539 GHz mainly in core #1, and acetone lines at 102.547 GHz in cores #1, #2, and #4.