High-precision Narrow Angle Astrometry with a Space-borne Interferometer

This paper develops all observing and processing scheme for narrow angle astrometry using it single baseline interferometer without the aid of "grid" stars to characterize the interferometer baseline vector in inertial space. The basic concept derives from the recognition that, over a narrow field the set, of fundamental unknown instrument parameters that arise because the interferometer baseline vector has large uncertainties (since there are no grid star measurements) is indistinguishable from a particular set, of unobservable errors in the determination of star positions with the field. Reference stars within the narrow field are used to circumvent these unobservable modes. Feasibility of the approach is demonstrated through analysis and example simulations.