The measured ZTF periods overlaid on the A. McQuillan et al. (2014) Kepler catalog. In the left panel, the orange crosses (N = 6265) indicate targets which did not pass the cut described in the text, while the blue circles (N = 272) indicate those that did. The horizontal streak of periods at ∼29 days is due to the lunar phase and are treated as systematics. The high-temperature cutoff is due to our threshold of T_eff < 5300 K and the increase of sources at T_eff < 4000 K is due to the way the TESS CTL is produced where the cool-dwarf list is included (P. S. Muirhead et al. 2018). The right panel is the same as the left panel but zoomed into the region where T_eff < 4000 K. We can see that our accepted periods trace out the shape present in A. McQuillan et al. (2014).