Spatial distribution of stars in our PM catalog, overlaid on the CTIO/Blanco ISPI K_S-band image of the ONC from Robberto et al. (2010). Open yellow and blue circles mark stars measured with HST and Keck (or Keck+HST), respectively. Open magenta circles mark Gaia DR2 sources with the astrometric_excess_noise=0 used in Kuhn et al. (2019). The dashed polygon illustrates the sky coverage of our 2010 and 2014 Keck NIRC2 data.