One round instrument per solar array, answering a single question at a glance: is this panel square to the sun right now? The outer ring is the sun. The inner mark is the panel's face. When the panel is aimed dead-on, the mark slides home to center, the capture arms close, and the pip locks. Off-axis, the mark drifts to the rim in the exact direction you're missing, so the gap is something you can see, not just read. Aim quality is carried by offset, aperture, pip shape, and a plain word, so it never depends on color.