Total AB magnitude in the r band from Nanni et al. (2020) as a function of spectroscopic redshift for the 122 Chandra J1030 sources with z_spec from M21 (open markers): we do not include in this plot the z = 6.3 QSO SDSSJ1030+0525, which is not detected in the r band. BL-AGN are plotted as blue circles, narrow-line AGN as red squares, emission line galaxies as cyan diamonds, and early-type galaxies as orange stars. The emission line galaxies reported in this work are plotted as full cyan diamonds.