Atomic spectroscopy experiments have reached a level where the transition line profile has become measurable with high precision. One of the most important task of such experiments is the determination of the transition frequency and an accurate comparison with the corresponding theoretical value. However, a detailed theoretical description of the line profile requires consideration of increasingly tiny effects which can play a crucial role in determining fundamental physical constants. In particular, it was shown recently that the nonresonant corrections arising in the description of the scattering processes of photon by atoms can lead to significant changes in the determination of the transition frequency. In present work, an adaptive method of moments for extracting the transition frequency from the experimental spectral data is discussed.