Found by a rational-parameter search of the Kubert-Tate family for torsion 8, at t=-10/21. In y^2+(1-c)xy-by=x^3-bx^2 the parameters are defined by b=(2*t-1)*(t-1);c=b/t; Converted to the global minimal model; PARI/GP ellrank returned bounds [3,3]. The 3 supplied points and the torsion subgroup are independently certified by the site.
David Renshaw ·