Observed spectrum of Ark 120. The B-band (blue shaded) traces the AGN (and host) continuum and a small (<5%) contribution by Hγ. The V-band (green shaded) traces the continuum and a small (<15%) contribution by Hβ. The narrow-band traces the continuum (black shaded) and Hβ (red shaded), each component contributing to about 50% to the band pass. The red wing of Hβ extending beyond [OIII] is neither seen in Hα nor in Hγ and could be due to Fe lines (Korista 1992). For the effective transmission curves of B and V see Fig. 1.