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S Rengaswamy, R. J. Allen (STScI)
The presence of companion sources within the ~ 2'' field-of-view of SIM limit its astrometric accuracy and thus enforce limits on its scientific performance. We are developing procedures to estimate the errors caused by such confusing sources, with the aim of understanding the the general nature and level of such errors and their possible severity for SIM's key projects. We model the errors taking the spectral type, magnitude, position and number density of the companion stars as free parameters. With the additional aim of assessing the calibration requirements and evaluating the effects of instrumental errors we parametrize the operation of SIM in terms of aperture size, number of channels (and hence the bandwidth), effective field-of-view, amplitude and phase instabilities, etc. We will present the results obtained with our software for a few simple source morphologies such as close and wide binaries and multiple star systems. We plan to extend our simulations to more complicated and crowded-field geometries such as open and globular clusters, center of Milky Way, AGN and other galaxies as required by the SIM Science Team. This work is being carried out with the STScI-JPL contract grant C4005.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.