I hereby declare that the work in this thesis is that of the candidate alone, except where indicated below. The co-authors of resulting papers contributed to the text of those papers.
Chapters 3, 4, 5, 6, 7, and 8: The Southern Hemisphere VLBI Experiment team contributed to the observations of radio sources described in these chapters.
Chapter 3: The VLBI data from 1991 March 13 were correlated and calibrated by D.W. Hoard (JPL) and J.E. Reynolds (ATNF).
Chapter 4: The VLBI data for PKS 0208-512, PKS 0438-436, PKS 0521-365, PKS 0537-441, and PKS 0637-752 were correlated partly by T.D. van Ommen (JPL).
Chapter 5: Correlation of VLBI data from 1991 March 6, 1991 November 24, 1992 March 26, and 1992 November 22 was undertaken by T.D. van Ommen, M, St. John, and D.W. Hoard (JPL). Fringe-fitting of VLBI data from 1991 March 6, 1991 November 24 and 1992 March 26 was undertaken by D.W. Hoard, M. St. John, and D.L. Meier (JPL). Calibration of VLBI data from 1991 March 6 and 1991 November 24 was undertaken by J.E. Reynolds (ATNF).
Chapter 6: The calibration files for the VLBI observations were prepared by J.E. Reynolds. Part of the correlation of the VLBI data was undertaken by A.K. Tzioumis (ATNF).
Chapter 7: The 22 GHz Tidbinbilla observations were conducted by E.A. King (ATNF) and P. Harbison (British Aerospace Australia). The ATCA imaging observations were supervised by A. Koekemoer (MSSSO).
Steven John Tingay
May 1996