The AN/SPQ-11 Cobra Judy was a PESA radar found on the USNS Observation Island (T-AGM-23) missile range instrumentation ship. It was used for space tracking, ballistic missiles tracking and other instrumentation. Cobra Judy was the Airforce code name for the afloat phased-array radar that was designed with a primary mission of monitoring Soviet missile tests and which operated in conjunction with land based phased-array radar Cobra Dane and Cobra Ball aircraft. Cobra Judy was replaced by the Cobra Judy Replacement (CJR) in April 2014.

Classification of radar systems

Under the Joint Electronics Type Designation System (JETDS), all U.S. military radar and tracking systems are assigned a unique identifying alphanumeric designation. The letters “AN” (for Army-Navy) are placed ahead of a three-letter code. Thus, the AN/SPQ-11 represents the 11th design of an Army-Navy “Ship-mounted, Radar, Special Purpose” electronic device.

Replacement

The Cobra Judy Platform, USNS Observation Island (T-AGM-23) was taken out of service and stricken from the Naval Vessel Register March 31, 2014. On 31 March 2014, the Cobra Judy Replacement program, aboard USNS Howard O. Lorenzen (T-AGM-25) reached initial operational capability (IOC). According to the Naval Sea Systems Command (NAVSEA), the U.S. Air Force also assumed operational and sustainment responsibilities for the ship. The inertial navigation system for the antenna stabilization and alignment had been provided by iMAR Navigation.