Building an Optimal Census of the Solar Neighborhood with Pan-STARRS Data

We estimate the fidelity of solar neighborhood (D < 100 pc) catalogs soon to be derived from Pan-STARRS astrometric data. We explore two quantities used to measure catalog quality: completeness, the fraction of desired sources included in a catalog, and reliability, the fraction of entries corresponding to desired sources. We show that the main challenge in identifying nearby objects with Pan-STARRS will be reliably distinguishing these objects from distant stars, which are vastly more numerous. We explore how joint cuts on proper motion and parallax will impact catalog reliability and completeness. Using synthesized astrometry catalogs, we derive optimum parallax and proper-motion cuts to build a census of the solar neighborhood with the Pan-STARRS 3 pi Survey. Depending on the Galactic latitude, a parallax cut pi/sigma(pi) > 5 combined with a proper-motion cut ranging from mu/sigma(mu) > 1-8 achieves 99% reliability and 60% completeness.