A transit-depth cross-scan varies the planet-to-star radius ratio across rows, showing how the blocked flux scales as depth = (R_p / R_s)^2. The arithmetic is exact only for the stated radius ratios and rows in the ideal uniform-disk, dark-planet model. Real observations add noise, calibration, extinction, limb darkening, cadence, geometry assumptions, and measurement/source uncertainty.
Three exact rows show radius ratio squaring into transit depth. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Transit depth squares the radius ratio
The checked source has radius ratio two fifths, so the depth is four twenty-fifths.
depth=(52)2=254
Radius ratio changes are squared in the depth
The rows show that increasing radius ratio from one fifth to three fifths changes depth from one twenty-fifth to nine twenty-fifths.