  We effect thermodynamical formalism for the non-uniformly hyperbolic
$C^\infty$ map of the two dimensional torus known as the Katok map. It is a
slowdown of a linear Anosov map near the origin and it is a local (but not
small) perturbation. We prove the existence of equilibrium measures for any
continuous potential function and obtain uniqueness of equilibrium measures
associated to the geometric $t$-potential $\varphi_t=-t\log |df|_{E^u(x)}|$ for
any $t\in(t_0,\infty)$, $t\neq 1$ where $E^u(x)$ denotes the unstable
direction. We show that $t_0$ tends to $-\infty$ as the size of the
perturbation tends to zero. Finally, we establish exponential decay of
correlations as well as the Central Limit Theorem for the equilibrium measures
associated to $\varphi_t$ for all values of $t\in (t_0, 1)$.
