The I Zw 1 type AGN: busy in X-rays but optically quiet

A sub-class of narrow-line Seyfert 1 galaxies with exceptionally strong Fe II emission lines named after the prototype I Zw 1 show high variability in X-rays. Despite this, and in contrast with many other Seyferts, variations in the optical are comparatively small. I have collected Las Cumbres Observatory robotic telescope network BVugr photometry of 19 I Zw 1 type AGN over 2-3 years and can compare their optical variability to that of other sub-classes of AGN. The study confirms that on average the relative optical luminosity fluctuations of I Zw 1 type AGN are significantly smaller. Possible physical interpretations of this result are explored.