Power-Law Continuum Fitting of Quasar Spectra: Wavelength Region Selection and Adjustments

Initially, we tentatively utilized the wavelength regions of 1250-1350, 1700-1800, 1950-2200, and 2650-2710 Å, as defined by Gibson et al. (2009), for each spectrum. By iteratively fitting the continuum within these wavelength intervals, we obtained a power-law continuum fit for each spectrum. Subsequently, we adjusted the wavelength intervals by assessing the effectiveness of matching between each power-law continuum and its corresponding initial spectrum. As a result, 18 out of 25 quasars' spectra were well-fitted with the wavelength regions proposed by Gibson et al. (2009) for the power-law continuum fit. However, the remaining seven quasars required different wavelength regions for fitting the power-law continuum, although these regions were consistent across different observations of the same quasar. For example, in the case of J091127.61+055054.1, the power-law continuum fit adopted the wavelength regions defined by Gibson et al. (2009) in the range of 1410-1510 Å, which exceeded its corresponding initial spectrum. Therefore, we adjusted it to 1250-1350, 1430-1440, 1470-1480, 1700-1800, 1950-2200, and 2650-2710 Å.