Currently and since 1967, the International System of units (SI) defines the time unit, the second in terms of an internal
property of an atom: the energy difference between the two hyperfine levels of the ground state of the cesium133 atom.
The National Center of Metrology in Mexico has developed the first experimental device in Latin America, called CsOp-
1 with the objective to reproduce the second with an accuracy of the order of 10-13 seconds. To reach this accuracy levels
has been necessary to take in account the effects that modify the energetic difference in the hyperfine energy levels of the
ground state of the cesium atom and evaluate the magnitude of the systematic shifts in the frequency n associated to the
difference between this hyperfine levels by the Plank equation E=hn. Among this effects are the followings: second-order
Zeeman effect, black body radiation, relativistic effect, and others. In this work we present a high accuracy evaluation of
this systematic effect in the level of parts in 1013, and also the evaluation of the associated uncertainties.
Currently the CsOp-1 is under frequency stability evaluation by making comparisons with others time and frequency
standards at CENAM