Using a large quantity of Rossi X-ray Timing Explorer data presented in the literature I offer a detailed investigation into the accuracy of quasiperiodic oscillations ( QPO ) frequency determination .
The QPO phenomenon seen in X-ray binaries is possibly a result of the resonance of the intrinsic ( eigen ) oscillations and harmonic driving forces of the system .
I show that the resonances , in the presence of the damping of oscillations , occur at the frequencies which are systematically and randomly shifted with respect to the eigenfrequencies of the system .
The shift value strongly depends on the damping rate which is measured by the halfwidth of the QPO feature .
Taking into account this effect I analyze the QPO data for four Z-sources : Sco X-1 , GX 340+0 , GX 5-1 , GX 17+2 and two atoll sources : 4U 1728-34 , 4U 0614+09 .
The transition layer model ( TLM ) predicts the existence of the invariant quantity : \delta , an inclination angle of the magnetospheric axis with respect to the normal to the disk .
I calculate \delta and the error bars of \delta using the resonance shift and I find that the inferred \delta - values are consistent with constants for these four Z-sources , where horizontal branch oscillation and kilohertz frequencies have been detected and correctly identified .
It is shown that the inferred \delta are in the range between 5.5 and 6.5 degrees .
I conclude that the TLM seems to be compatible with data .