IRAC1 – IRAC2 vs. IRAC2 for XXL-S radio sources. The red circles are galaxies that have been classified as AGN according to their SED fit, the blue circles galaxies that have been classified as X-ray AGN, and the cyan circles both SED and X-ray AGN. The solid lines are the Assef et al. (2013) lines modified for use with the IRAC data (IRAC1 – IRAC2 = 0.67 and Eq. (12)). For comparison, the original Assef et al. (2013) curves for WISE are shown as dashed lines.