CO J = 3 → 2 spectra obtained with the APEX telescope. Fluxes are in Jy with respect to LSR velocity. The last box shows the cumulated spectrum made with spectra shifted in velocity to set the systemic velocity to zero (multiplied by factor five). The sources with a high rms or showing strong contamination (i.e., HD 17848 and HD 166191) are not used to produce the cumulated spectrum. The 3σ upper limit model for each spectrum is over-plotted in red (see sect. 3.3).