Best-fitting results (top panel) and corresponding residuals (bottom panel) to the ZTF g/r-band light curves by two sinusoidal components. Top panel: Circles plus error bars in blue and in red show the ZTF g-band and r-band light curves, solid orange lines represent the best-fitting results, dashed orange lines indicate the 5σ (99.99994%) confidence bands, and dashed purple lines show the polynomial components. The dashed blue and solid blue lines show the sinusoidal components with periods of 1024±12 days and 222±1 days in the ZTF g-band light curve, and the dashed and solid lines in red represent the sinusoidal components with periods of 886±6 days and 257±1 days in the ZTF r-band light curve.