Time-resolved Lomb-Scargle analysis of the Kepler data. A sliding window of 19 days was used, with each window shifted by a step size of 0.2 days. The horizontal black lines and the ticks on the right side of the diagram indicate time steps where the amplitude of the first harmonic exceeds that of the fundamental, supporting the interpretation of stellar spots. No significant signal is observed beyond 2.5 cd⁻¹.