Observed time delay spectrum for multiple delay estimation methods. Time delays were measured using the interpolated cross-correlation function (ICCF; Gaskell & Peterson 1987 black circles), JAVELIN (Zu et al. 2011) damped random walk modelling (blue squares), the z-transformed discrete correlation function (ZDCF; Alexander 1997 yellow triangles), and the von Neumann statistical estimator (VN; Chelouche et al. 2017 red open circles), with error bars corresponding to 1σ uncertainties. A small shift in wavelength has been introduced for clarity. The close agreement between delays obtained by different methods demonstrates the robustness of the measurements, supporting the reliability of the wavelength-dependent delay structure observed in the quasar’s variability.