Top: GLS periodograms of light curves. Solid red, blue, and green lines show the corresponding results from the CSS V-band and ZTF r- and g-band light curves. The horizontal dashed red lines indicate the corresponding 5σ significance level (FAP = 3e-7). Middle and bottom: Distributions of the periodicity determined via the bootstrap method from the CSS V-band light curve and the ZTF g- and r-band light curves.