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 describing the aberration).
This design is common for large telescopes, including:
Large Altazimuth Telescope (BTA-6)