Histogram of the optical magnitude for our blazar candidates (gray) compared to BZCAT-matched sources (yellow), inclduing FSRQs (light red; partially overlapping with BZCAT due to transparency). Only a subset of the candidates is already known as blazars. The BZCAT sources peak at around i_η ∼ 18 − 19, while the candidate sample extends to significantly fainter magnitudes at i_η ∼ 20.