Keywords:nulling interferometry; high - contrast imaging; exozodiacal dust
Publisher:Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2006.
Citation:SPIE Astronomical Telescopes and Instrumentation, Orlando, Florida, May 24 - 31, 2006.
Abstract:
This paper presents an overview of the observing and data reduction strategies used to produce a calibrated measurement of the off-axis light. During the observations, the instrument cycles rapidly through several calibration and measurement steps, in order to monitor and stabilize the phases of the fringes produced by the various baselines, and to derive the fringe intensity at the constructive peak and destructive null along the long baseline. The data analysis involves removing biases and coherently demodulating the short-baseline fringe with the long-baseline fringe tuned to alternate between constructive and destructive phases, combining the results of many measurements to improve the sensitivity, and estimating the part of the null leakage signal which is associated with the finite angular size of the central star. Comparison of the results of null measurements on science target and calibrator stars permits the instrumental eakage - the “system null leakage” - to be removed and the off-axis light to be measured.