Parent an object to a particle world producer?

Hi, I'm trying to parent a null object to a particle world producer's positional value, but because they use different values, it's in the completely wrong spot.

I found an expression to do the opposite, of parenting the particle producer to an object, but idk how to reverse engineer it to get it to do what I want.

var p = thisComp.layer("Emitter").transform.position[0]-thisComp.width/2;

p/thisComp.width;

What I'm trying to do is have a light source's point of interest follow the particle producer but since you can't split the point of interest dimensions I'm parenting that to a null object, splitting it's dimensions, and trying to parent each of the producers dimensions to the null objects

I'm also editing video that's 4096x2304 which I think might be relevant