Comparison of the results for the star HD 37394 using BGLST model and GLS models with and without detrending. Panel a: data (black crosses), BGLST model (red continuous curve), GLS model fitted to detrended data with trend added back (blue dashed curve), GLS model fitted to the original data (green dash-dotted curve), trend component of the BGLST model (red line) and empirical trend (blue dashed line). Panel b: spectra of the models with the same colours. Vertical lines mark the locations of the corresponding maxima.