A circular swarm of 15 dots orbits a central point, with each dot’s opacity oscillating between transparent and fully opaque as the animation updates 60 times per second. The visualization uses D3 7.9.0’s `select`, `range`, and `selectAll` APIs to render SVG circles, with position and opacity derived from sine and cosine functions of an incrementing time parameter. Data is generated procedurally in `makeData` and passed to the `vizData` renderer, which updates circle attributes via D3’s join operation.