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We present a reverberation analysis of the strong, variable optical Fe IIemission bands in the spectrum of Akn 120, a low-redshift AGN which is one ofthe best candidates for such a study. On time scales of several years the Fe IIline strengths follow the variations in the continuum strength. However, we areunable to measure a clear reverberation lag time for these Fe II lines on anytime scale. This is due to the very broad and flat-topped nature of the Fe IIcross correlation functions, as compared to the H-beta response which is muchmore sharply localized in time. Although there is some suggestion in the lightcurve of a 300-day response time, our statistical analysis does not pick upsuch a feature. We conclude that the optical Fe II emission does not come froma photoionization-powered region similar in size to the H-beta emitting region,but we cannot say for sure where it does come from. Our results are generallyconsistent either with emission from a photoionized region several times largerthan the H-beta zone, or with emission from gas heated by some other means,perhaps responding only indirectly to the continuum variations.

On the size of the Fe II emitting region in the AGN Akn 120