For n=19 I sampled similarity transforms (rotation, scale, translation) of the published point set, rounded each transformed coordinate to the nine-decimal unit-square grid, and evaluated max/min pairwise squared distances with exact integer arithmetic. The best grid transform has ratio 3.863703306430753..., which rounds upward to 3.863703307 versus 3.863703315 previously. The same transform-and-round procedure is reproducible for other P52 rows.
P52 · Smallest ratio of largest to smallest distance · Discussion