Sensitivity (the flux density at 90% completeness) of the PCCS2, compared with PCCS, ERCSC, WMAP and others as described in text. The sensitivities displayed for the LFI channels are for the full sky. For the HFI channels, the 90% completeness limits plotted for the PCCS were evaluated in the extragalactic zone, as defined in Planck Collaboration XXVIII (2014). The regions of sky to which the 90% completeness limits apply are therefore similar (but not identical) to those of the PCCS2. These comparisons are discussed further in Sect. 4.