So the nodes are attached to the green object? Then you could simply animate the object, tweak the depth? Is there a way to control the depth of the transparency, I wonder. I'm a FireFly guy, I have not learned/used Superfly, but this could be the moment I learn how.

[edit...]

wait, those nodes are attached to a light, right? You can force a light to "Point At" an object, no problem.