I think the laser/ maser does the work. Why it is not discerned is cause for concern, something like mass hypnosis when nigh on a hundred people are keeping watch, and yet not one of them sees the circle "happen".

The ball of light is one of the first manifestations of the simple optical laser in a field setting. Think painting targets, as a basic example, but the very old concept of the ball of light as the scurrying tool of Mages and Wizzards, those would have much mote complexity and a small aspect of sentience.

I find it difficult to ascribe the creating to the ball of light.
More likely, the laser jocky is getting in some real world practice in pattern tracking. So unromantic, but its likely government, not Mages, much as some might hope for such an enlightened being, the venue seems far too public!