The automated detection and analysis of gravitational microlensing events

[摘要] ENGLISH ABSTRACT:In this thesis we addressed some issues concerning the automation of the detection, processingand the analysis of gravitational microlensing events, which are currently beingused in the search for extra-solar planets.We were provided with a series of data images containing a microlensing event. Usingthese images we address several practical problems: registration, background subtractionand some PSF modelling.Registration is accomplished by using the intersection points of circular arcs drawn aroundstellar objects. After which the influence of the sky background is removed by using thewatershedding algorithm and plane fitting.Our analysis is based on relative brightness - to counter seeing, the brightness of starsare calculated by isolating the objects from the background and summing over the area.A brightness variation curve is plotted and the trend of the lensing event and the posi tionof a blip are extracted using wavelets, calculating general trends and LOESS.The trend of the brightness variation curve can be used for both identification and classificationof various events. It can also be used for the identification and classification ofvariable stars. Blip analysis is used to detect the presence of a planet (or dark body) inthe vicinity of the source.

[发布机构] Stellenbosch University