%0 Generic
%A Kaminski, Adrian
%D 2013
%F heidok:15667
%R 10.11588/heidok.00015667
%T The Search for Extrasolar Planets  by the Means of High Precision Astrometry  with the Dual-Feed Interferometer PRIMA
%U https://archiv.ub.uni-heidelberg.de/volltextserver/15667/
%X Several hundred extrasolar planets have been discovered until today. The most commonly applied  detection methods are indirect and therefore typically limited in determining the whole set of the  orbital parameters and in characterizing the specific planets. Among these, astrometry serves as an  important complementary technique, as the orbital inclination and the planet's true mass can be  derived from the two-dimensional measurements of the host star's reflex motion due to the presence  of a companion. The VLTI's dual-feed interferometer PRIMA has been developed to provide high  precision differential astrometry at the level of tens of microarcseconds, by which Saturn-like planets  around nearby stars would become detectable. This is accomplished by simultaneous phase-referenced  fringe tracking on two sources within the isoplanatic angle. Within this thesis the instrument's overall  performance during commissioning is examined. Stable fringe tracking on both sources is generally  achieved, and the effect of phase referencing is evident. However, phase jumps during the observations  are reported, which might be due to phase shift offsets between the spatially modulated reference  signals, from which the phases are recovered. These are investigated. An analysis of the discrepancy  between the achieved astrometric precisuins on short and long time scales reveals hidden but evident  systematic errors.