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T.J. Shen, R. Goullioud, J. Catanzarite, M. Shao, J. Yu, R. Machuzak (JPL)
The Microarcsecond Metrology Testbed (MAM) developed at the Jet Propulsion Laboratory is a single-baseline interferometer coupled with a precision pseudostar. It is designed to test the ability of the SIM science interferometer to perform microarcsecond stellar astrometry over both narrow-angle (1 degree) and wide-angle (7.5 degree) fields. The MAM Testbed features an optical interferometer with a white light source, all major optical components of a stellar interferometer and heterodyne metrology sensors. This paper will describe the performance metric used to evaluate our narrow-angle field dependent data and presents the results of the analysis.
The narrow-angle 3 star observation scenario implemented in the MAM testbed consists of 1 target (T) star and 2 accompanied reference (R1,R2) stars, which are 1 degree apart horizontally from the target star. The observation of target (science) and reference stars are interlaced (R1,T,R2,T,repeat) in order to remove temporal and spatial drifts between consecutive measurements of the target star. The total observation time for target star is twice that of the 2 reference companions. Cyclic averaging was implemented in our observations in addition to interlacing.
The least squares algorithm tested in our field independent measurements is applied to solve for the delays (or paths) of the target star and the 2 reference stars. A super chop variance was adopted as our performance metric. This super chop variance will remove the drifts of the target star path from its path differences with respect to the 2 reference stars. Recent data is presented which demonstrates agreement between the metrology and starlight paths to be better than 150pm in the 3 star narrow angle field of view.
The research described was performed at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Sp ace Administration.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.