Top panel: Q2 to Q17 photometric long-cadence observations (in ppm) of KIC 10644253 collected over 1422 days by the Kepler satellite as a function of time. Middle panel: magnetic activity photometric proxy S_ph (in ppm, black line) of KIC 10644253 estimated from the long-cadence observations as a function of time compared to the mean frequency shifts of the visible modes obtained from the cross-correlation analysis (Method #1, in μHz, blue squares). The frequency shifts were extracted from the continuous short-cadence observations from Q5 to Q17. Bottom panel: same as the middle panel but for the frequency shifts of the individual angular degrees l = 0 (gray triangles) and l = 1 (red circles) extracted from the local peak-fitting analysis (Method #2). The associated mean uncertainties are illustrated in the upper lefthand corner of each panel using the same color/symbol code. In the three panels, the vertical dotted lines represent the observational length of each Kepler quarter from Q0 to Q17.