Velocity V_LSR and velocity dispersion σ_v of the best Gaussian fit for C¹⁸O emission. Gaussian fits are only done for spectra with S/N > 4. The primary beam FWHM size is represented with a white dashed circle. The beam size is represented in a white ellipse in the bottom left corner. Top: central velocity of the best fit Gaussian profile for each spectrum. The black contour shows the same region plotted in the right panel of Fig. 2, from where the mass is calculated. Bottom: velocity dispersion of the best fit Gaussian profile for each spectrum.