Left: postage stamp of the X-ray and type-1 AGN host proto-BCG of Cl J0227-0421. Blue, green, and red channels are assigned to the i′K_s [4.5] bands, respectively, and logarithmic scaling is used for the brightness. Image dimensions are 25″ (~200 kpc at z ~ 3.3) on each side. The bright object to the north-northwest of the proto-BCG was not targeted by spectroscopy, but has a well-fit photometric redshift of z_phot = 1.21 ± 0.03. Right: observed-frame optical/NIR spectral energy distribution (SED) of the proto-BCG with the best-fit galaxy template overplotted in red. The proto-BCG has a power-law continuum both in the UV and in the IR, suggesting the physical parameter estimates coming from the SED fitting process are contaminated by the presence of the AGN. The best-fit stellar mass and luminosity-weighted stellar age are shown in the upper left corner of the plot.