The Observatory has called an end to a procedure that proves time really is money - the practice of sending officers to Japan on first-class flights to calibrate an atomic clock. The expensive missions were necessary because the delicate computer-like Caesium beam atomic clock had to be carried by hand to Tokyo where calibration could be done at the Communications Research Laboratory. The accuracy of Hong Kong's clock is essential for scientists and technical professionals. Normally, calibration has to be done every two to three years to maintain the accuracy of the clock to a deviation of less than 1 microsecond (a millionth of a second) a day. This variation would represent a loss of only one second every 2,740 years. But the mission is no longer required. From this year, the Observatory will rely on new satellite technology that allows atomic clocks around the world to be checked remotely.