Comparison of the results using various models. The true model of the data contains one harmonic, a trend, and additive white Gaussian noise. Panel a: Data (black crosses), BGLST model (red continuous curve), GLS-T model (blue dashed curve), GLS model (green dash-dotted curve), true trend (black dotted line), trend from BGLST model (red continuous line), and empirical trend (blue dashed line) are shown. Panel b: spectra of the corresponding models with vertical lines indicating the locations of maxima. The black dotted line shows the position of the true frequency.