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| Paper: |
Accuracy and Stability of Fringe Measurements in SIM |
| Volume: |
351, Astronomical Data Analysis Software and Systems XV |
| Page: |
299 |
| Authors: |
Pan, X.; Shao, M. |
| Abstract: |
In order to identify habitable planets beyond our solar system it is necessary to determine their masses. SIM PlanetQuest is the only space mission which can discover and measure planets as small and cool as those in our solar system. This mission, however, requires unprecedented accuracy of angular measurements to the level of a microarcsecond, which are three orders of magnitude better than the accuracy of the recent space astrometric missions. For microarcsecond accuracy of astrometric measurements the corresponding fringe delay must be determined to the accuracy of picometers and it is a challenging task to measure fringe delays to this level of precision. Several testbeds in SIM have been established in order to check critical techniques and to validate estimation of fringe parameters. Many instrumental errors such as beam walk, cyclic errors, vibrations, alignment errors, visibility losses, wavefront distortions and thermal drift are investigated. Also lessons learned from the Hipparcos mission lead us to further study of possible systematic biases. By using Full Aperture Metrology (FAM) wavelength calibration we show significant differences between stability and systematic offset of fringe measurements. A new calibration procedure is proposed. |
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