Spectral sensitivity of CONCERTO. For a one second integration and a reference beam of 30 arcsec FWHM, the noise level is shown as a function of frequency (solid black curve) per spectral element of 3 GHz, for an average pwv of 0.4 mm. The dashed cyan curve represents the instrumental noise, estimated with the measured noise outside the CONCERTO bandpass, extrapolated to CONCERTO frequencies assuming white noise, and converted to physical units using the spectroscopic response without atmospheric correction.