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Paper: Differential Astrometry with the Keck Interferometer
Volume: 194, Working on the Fringe: Optical and IR Interferometry from Ground and Space
Page: 84
Authors: Boden, A. F.; Colavita, M. M.; Lane, B. F.; Shao, M.; van Belle, G. T.; Lawson, P. R.
Abstract: A principle operating mode of the Keck Interferometer (KI) will be to perform narrow-angle differential astrometry on nearby stars to detect and characterize the masses and orbits of planetary companions and planetary systems. To achieve this goal KI will be able to perform 20-uas differential astrometry over a 20 - 30" field. In this talk I will discuss the scientific potential for KI in conducting an astrometric census of nearby stars, the technical operating principles of ground-based long-baseline differential astrometry, and the realization of these techniques with the KI facility. An integral part of the KI differential astrometry development is the differential astrometry engineering effort at the Palomar Testbed Interferometer (PTI). Our engineering goal at PTI is to demonstrate 60 uas narrow-angle astrometry over a 30" field. Last year (1998) at PTI we were able to demonstrate multi-night astrometric precision of approximately 300 uas on the long-period binary star 61 Cygni. I will discuss these PTI results, what we have learned from them, and their implications both for our PTI efforts this year, and the application of this work in the KI astrometry implementation.
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