If ${\mathrm{S}}_1,{\mathrm{S}}_2$ are foci of the ellipse  $\frac{x^2}{13}+\frac{y^2}{4}=1$ and $\mathrm{P}(\alpha ,12-2\alpha )$ be a variable point in the same plane such that $\angle {\mathrm{S}}_1{\mathrm{PS}}_2\left(\text{ angle }{\mathrm{S}}_1{\mathrm{PS}}_2\right)$ maximum, then the possible value of $\frac{{\mathrm{S}}_1\mathrm{P}}{{\mathrm{S}}_2\mathrm{P}}$ is equal to