A telescope having a spherical primary mirror and a specially figured correcting plate, and a special mounting for tracking artificial satellites. The optical system was designed by J. A. Baker and the mounting by J. Nunn. It is a variation of the Schmidt type, with the focal surface having a toroidal shape instead of a spherical shape. The correcting plate contains three elements, giving an aperture of 50 cm and a focal length of 50 cm. The field of view is 5° by 30°. The mounting is of the alt azimuth type but allows tracking in right ascension and declination also. The optical system and mounting together allow a 12 th magnitude star to be photo-graphed when the direction of pointing is fixed, or allow an object of 8. 5 magnitude moving at 0. 1° per second to be photographed when the telescope is following the motion.