Estimation of the fractional frequency shift produced by the systematic physical phenomena of the national time and frequency standard, basis of the UTC scale (INM) in order to analyze the limitations in the stability of the cesium atomic oscillator

This study evaluates the historical stability of three cesium atomic oscillators marking legal time at the National Metrology Institute of Colombia since 2016. The frequency shifts are estimated based on systematic physical effects such as blackbody radiation, second-order Zeeman effect, gravitational effect, Stark effect, Zeeman AC and Doppler shift. The internal parameters of the oscillators, such as temperature and magnetic field current, are monitored to estimate the frequency shifts. An uncertainty budget is presented, and the total frequency shifts are determined for each oscillator, emphasizing the main contribution of the second-order Zeeman effect. The average frequency deviation for each oscillator is of the order of 10−10, which is consistent with the literature.