Hewlett Packard HP 5061A Caesium Beam Frequency Standard, originally serving as one of a suite of ‘atomic clocks’ from the mid 1960’s onwards by the Greenwich Time Service, when it was based at the Royal Greenwich Observatory, Herstmonceux, Sussex. Hewlett Packard Caesium Beam Frequency Standard used at Royal Greenwich Observatory, Herstmonceux 1970-1978
Atomic Oscillator Clock, Model FRK, by Efratom GmbH, Munich, as used to baseline the key concepts and hardware for the Global Positioning System (GPS) 1971-1974, and presented complete with gold cover to Hugo Fruehauf, the Chief Engineer for the GPS system, upon his departure from Efratom in 1996. Atomic Oscillator Clock 1960-1996