Left: integrated CO(2-1) line emission map from Berné et al. (2014), obtained with the IRAM 30 m telescope, in K km s^–1, re-projected into CONCERTO coordinates after convolution to an effective FWHM of 40 arcseconds. Right: Integrated CO(2-1) line map measured by CONCERTO. The integrated line intensity (in K km s^–1) is derived using Eq. (10), after subtracting the continuum. The map is convolved with a 30 arcsec Gaussian kernel to reach an effective FWHM of 42 arcseconds.