A Ritchey-Chrétien telescope (RCT or RC) is a reflector telescope with a specific reflector configuration of two hyperbolic mirrors, designed to limit telescope-induced aberrations. The primary mirror is hyperbolic but very close to parabolic. The secondary mirror is convex and hyperbolic. Curvature is chosen to eliminate third-order coma (the cubed term of a series-expansion that describes the aberration).
This design is common for large telescopes, including: