Spectra of C¹⁷O, H¹³CO⁺, C³⁴S, both C₂H doublets andboth c−C₃H₂ transitions for three different regions: the position of Oph-IRS67B (left column), the position of Oph-IRS67A (middle column) and the high-density region (right column). Spectra from panels a–i are rebinned spectrally by a factor of 4, while panels from j–u are rebinned spectrally by a factor of 2, so that all spectra have the same spectral resolution (0.43 km s⁻¹). The dashed black horizontal line shows the value of 3σ (σ = 3 mJy beam⁻¹ km s⁻¹). All spectra have been shifted to the systemic velocity (4.2 km s⁻¹; grey vertical line). The solid blue and red lines indicate the offset of the peak velocity determined from a Gaussian fit (see Table 4). The dashed blue line in the right column represents a velocity of −1.7 km s⁻¹. Some spectra have been multiplied by a scaling factor as indicated in the top left corner.