Example spectra illustrating the better performance of the improved fitting routine of GAUSSPY+ (Sect. 3.2.3) compared to the original GAUSSPY algorithm. Upper (a, b), middle (c, d), and lower (e, f) panels: synthetic spectra from samples B, C, and D, respectively. The panels on the left (a, c, e) show the decomposition results obtained with the original GAUSSPY algorithm and panels on the right (b, d, f) show the corresponding decomposition results from the improved fitting routine of GAUSSPY+. The correct individual Gaussian components are indicated in dashed black lines; individual Gaussian components and their combined intensity from the decomposition run with GAUSSPY and GAUSSPY+ are indicated in solid red and blue lines, respectively. The smaller panels below the spectrum show the corresponding residual with the dotted black lines indicating values of ±σ_rms. Dashed black lines indicate a S/N of 3. Blue and red shaded areas show the automatically identified signal and noise spike intervals, respectively.