The pairs of congruent circles tangent to each other at the points of tangency of the common tangent of (O1) and (O2) and to the circle (O') on diameter O1O2 are Archimedean and form two Powerian pairs [van Lamoen, 2007].
These Archimedean circles are also tangent to the circle with center O' passing through the point S2 where the Schoch line meets (O). [van Lamoen, 2007]