Taking the Measure of the Universe: Precision Astrometry with<i>SIM PlanetQuest</i>
Taking the Measure of the Universe: Precision Astrometry with<i>SIM PlanetQuest</i>
Precision astrometry at microarcsecond accuracy has applications for a wide range of astrophysical problems. This paper is a study of the science questions that can be addressed using an instrument with flexible scheduling that delivers parallaxes at about 4 μas on targets as faint as V = 20, and differential …