Activity Number:
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367
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Type:
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Topic Contributed
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Date/Time:
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Wednesday, August 1, 2007 : 8:30 AM to 10:20 AM
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Sponsor:
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Section on Bayesian Statistical Science
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Abstract - #309548 |
Title:
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An Exploratory Statistical Study of the Measured Motion of the Guide Star Used in a New Test of Einstein's Universe
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Author(s):
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Jingchen Liu*+ and Xiao-li Meng and Michael Ratner and Irwin Shapiro
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Companies:
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Harvard University and Harvard University and Harvard-Smithsonian Center for Astrophysics and Harvard-Smithsonian Center for Astrophysics
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Address:
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1 Oxford Street, Cambridge, MA, 02138,
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Keywords:
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Abstract:
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General relativity predicts that the phenomenon of "frame-dragging" slowly alters the direction of spin of Earth-orbiting gyroscopes. NASA's Gravity Probe B satellite measured the orientation of such freely falling gyroscopes with respect to a guide star. This star's motion with respect to "fixed points" in the distant universe thus needed to be measured independently. VLBI measurements spread over 14 years yielded 39 positions of this radio-emitting guide star. We use Bayesian methods and a linear regression model of the star's motion to study the effects of various assumptions involving the parameters of both the physical model and the measurement noise model. We find that a wide range of different assumptions lead to a narrow range of point estimates and error distributions.
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