Order 9 automorphisms of K3 surfaces
K<t> := FunctionField(Rationals());
E := EllipticCurve([K | 0, t^4*(t^3+1)^2]);
R<x, y> := FunctionField(E);
ER := BaseChange(E, R);
p := ER![x, y, 1];
q:= ER![0,t^2*(t^3+1),1];
3*q;
p+q;