The analysis of some bivariate astronomical time series

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dc.contributor.advisorZucchini, Walteren_ZA
dc.contributor.authorKoen, Marthinus Christoffelen_ZA
dc.date.accessioned2016-02-29T12:01:56Z
dc.date.available2016-02-29T12:01:56Z
dc.date.issued1993en_ZA
dc.descriptionBibliography: pages 75-76.en_ZA
dc.description.abstractIn the first part of the thesis, a linear time domain transfer function is fitted to satellite observations of a variable galaxy, NGC5548. The transfer functions relate an input series (ultraviolet continuum flux) to an output series (emission line flux). The methodology for fitting transfer function is briefly described. The autocorrelation structure of the observations of NGC5548 in different electromagnetic spectral bands is investigated, and appropriate univariate autoregressive moving average models given. The results of extensive transfer function fitting using respectively the λ1337 and λ1350 continuum variations as input series, are presented. There is little evidence for a dead time in the response of the emission line variations which are presumed driven by the continuum. Part 2 of the thesis is devoted to the estimation of the lag between two irregularly spaced astronomical time series. Lag estimation methods which have been used in the astronomy literature are reviewed. Some problems are pointed out, particularly the influence of autocorrelation and non-stationarity of the series. If the two series can be modelled as random walks, both these problems can be dealt with efficiently. Maximum likelihood estimation of the random walk and measurement error variances, as well as the lag between the two series, is discussed. Large-sample properties of the estimators are derived. An efficient computational procedure for the likelihood which exploits the sparseness of the covariance matrix, is briefly described. Results are derived for two example data sets: the variations in the two gravitationally lensed images of a quasar, and brightness changes of the active galaxy NGC3783 in two different wavelengths. The thesis is concluded with a brief consideration of other analysis methods which appear interesting.en_ZA
dc.identifier.apacitationKoen, M. C. (1993). <i>The analysis of some bivariate astronomical time series</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Statistical Sciences. Retrieved from http://hdl.handle.net/11427/17341en_ZA
dc.identifier.chicagocitationKoen, Marthinus Christoffel. <i>"The analysis of some bivariate astronomical time series."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Statistical Sciences, 1993. http://hdl.handle.net/11427/17341en_ZA
dc.identifier.citationKoen, M. 1993. The analysis of some bivariate astronomical time series. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Koen, Marthinus Christoffel AB - In the first part of the thesis, a linear time domain transfer function is fitted to satellite observations of a variable galaxy, NGC5548. The transfer functions relate an input series (ultraviolet continuum flux) to an output series (emission line flux). The methodology for fitting transfer function is briefly described. The autocorrelation structure of the observations of NGC5548 in different electromagnetic spectral bands is investigated, and appropriate univariate autoregressive moving average models given. The results of extensive transfer function fitting using respectively the λ1337 and λ1350 continuum variations as input series, are presented. There is little evidence for a dead time in the response of the emission line variations which are presumed driven by the continuum. Part 2 of the thesis is devoted to the estimation of the lag between two irregularly spaced astronomical time series. Lag estimation methods which have been used in the astronomy literature are reviewed. Some problems are pointed out, particularly the influence of autocorrelation and non-stationarity of the series. If the two series can be modelled as random walks, both these problems can be dealt with efficiently. Maximum likelihood estimation of the random walk and measurement error variances, as well as the lag between the two series, is discussed. Large-sample properties of the estimators are derived. An efficient computational procedure for the likelihood which exploits the sparseness of the covariance matrix, is briefly described. Results are derived for two example data sets: the variations in the two gravitationally lensed images of a quasar, and brightness changes of the active galaxy NGC3783 in two different wavelengths. The thesis is concluded with a brief consideration of other analysis methods which appear interesting. DA - 1993 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1993 T1 - The analysis of some bivariate astronomical time series TI - The analysis of some bivariate astronomical time series UR - http://hdl.handle.net/11427/17341 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/17341
dc.identifier.vancouvercitationKoen MC. The analysis of some bivariate astronomical time series. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Statistical Sciences, 1993 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/17341en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Statistical Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherStatistical Sciencesen_ZA
dc.subject.otherAstronomyen_ZA
dc.titleThe analysis of some bivariate astronomical time seriesen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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