CO(1–0) and CO(2–1) spectra (left and right columns) observed with the IRAM 30 m telescope at the five positions observed in the IGM of the SQ group (see Figure 1). CO emission with multiple velocity components is detected at all positions: in the shock, in SQ-A, and in the bridge regions. The red line shows the result of the line fitting (see Tables 2 and 4 for the decomposition in multiple Gaussian components for each transition). The spectra have been smoothed to a spectral resolution of 40 km s ⁻¹. Note that the CO(1–0) and CO(2–1) beams do not match, and that the detection of the CO(2–1) line in the Ridge 3 position is tentative (in this case the Gaussian fitting—dashed line—is not reliable). The arrows indicate the pre-shock H i velocities for the intruder galaxy and the intra-group medium.