WISE data at 3.4, 4.6, 12, and 22µm have been coadded on exactly the same image projection system as the ultra deep IRAC coadds. As the figure below illustrates, the WISE data (B&W) fully encompass the limits of the IRAC data (blue). The WISE data are very deep because WISE re-observed the north ecliptic pole every orbit; in fact, the shorter wavelengths are confusion limited, albeit shallower than IRAC given the very large WISE beam.