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 $\sim$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.