The Circumcircle And The Tangents

Geometry

Two circles $\omega_1$ and $\omega_2$ intersect at points $A$ and $B$ . The tangent to $\omega_1$ passing through $A$ intersects $\omega_2$ at $X$ . The tangent to $\omega_2$ passing through $A$ intersects $\omega_1$ at $Y$ . Let $O$ be the circumcenter of $\triangle XAY$ . Then what is the measure of $\angle OBA$ in degrees?