Caesium Beam Atomic Clock

Today, the Observatory’s time service is based on the caesium beam atomic clock. The latest generation of caesium beam atomic clocks is the product of 40 years of technological evolution since the first caesium beam atomic clock acquired in 1980. Nowadays, it has an accuracy within 0.01 millionths of a second per day.

“Cool Met Stuff”: 40 Years of Caesium Beam Atomic Clock (Cantonese only)