Top panel: the GLS periodogram ﹩{\hat{S}}^{LS}({f}_{k})﹩ (green) of KIC 6102338 flux with the best-fit AR(1) (purple solid line), power law (red dashed line), and white noise (black dashed–dotted line) models. The star’s rotation signals and harmonics with frequency 1/P₀ are represented by the vertical navy dashed lines and 1/P₁ by vertical violet dashed lines, Bottom panel: the red noise 5% (red), 1% (orange), and 0.1% (blue) FALs and the 1% white noise FAL (black dashed line) are shown. Peaks at frequency 1/P₀ and its first harmonic 2/P₀ reach the 99.9% significance level while the signal at frequency 1/P₁ reaches the 99% significance level in the red noise FALs.