Measuring Stellar Rotation in the K2 Sample

We have used a combination of techniques to measure rotation periods for over 200,000 stars from K2. We compute autocorrelation functions for each star's "everest" light curve (Luger et al. 2018) to identify significant peaks corresponding to stellar rotation periods. We optimize a Gaussian process rotation model and perform MCMC to obtain a second estimate of the rotation period with error bars. The bimodal rotation period distribution discovered in Kepler by McQuillan et al. (2013) and extended with Gaia by Davenport and Covey (2018) is also detected here in the K2 sample. We explore the origin of this period bimodality, as well as the rotation period gradient across the main sequence noted in Davenport and Covey (2018). The data products resulting from this work, including rotation period estimates and associated uncertainties, will be made available to the community. We are also applying the same tools used here on K2 data to light curves from TESS.