20,000 Rotation Periods in Nearby Open Clusters and Moving Groups from ZTF and ASAS-SN

Open clusters provide uniquely powerful laboratories for studying stellar evolution because their members share a common age and chemical composition. Stellar rotation of low-mass GKM dwarfs in open clusters provides direct empirical constraints on magnetic braking, with implications for stellar interiors, magnetic activity, and star--planet interactions. However, existing cluster rotation samples are dominated by space-based observations, whose limited spatial coverage and short observing baselines can make it difficult to construct an unbiased sample. Long-baseline ground-based time-domain surveys therefore provide an important complement to space-based photometry. I present a catalog of about 20,000 periodic photometric signals, including stellar rotations, eclipsing-binaries, and classical pulsators, measured from the Zwicky Transient Facility (ZTF) and the All-Sky Automated Survey for Supernovae (ASAS-SN) for members of nearby open clusters and moving groups within 1.5 kpc. This catalog provides a new empirical foundation for studying the mass, chemical composition, and age dependence of stellar angular-momentum evolution and for testing models of magnetic braking across a broad range of stellar masses and evolutionary states.