KH-4B 6 (Corona 131) & P-801 2

The KH-4B (Keyhole-4B) marked the sixth iteration within the Corona program for optical reconnaissance satellites. It was equipped with two J-3 panoramic cameras, each with a focal length of 61 cm, providing a ground resolution of 1.8 meters and a ground swath of 16 km × 217 km. Additionally, the KH-4B featured the DISIC (Dual Improved Stellar Index) camera, offering superior mapping capabilities compared to the KH-5 Argon system. The DISIC camera had a focal length of 91 cm, providing a ground resolution of 30 meters, with a frame coverage of 260 km × 260 km.

The P-801 (or Program 801) satellites were a special series among the so called "Subsatellite Ferrets", low orbit ELINT/SIGINT satellites to pinpoint and characterize different Radar emitters in the Soviet Union and Warsaw pact states. Before their program name was known, they are referred to as "Subsatellite Ferret C" (SSF-C).