
%0 Journal Article
%A Jauncey, D. L. 
%A King, Edward A. 
%A Bignall, Hayley E. 
%A Lovell, J. E. J. 
%A Kedziora-Chudczer, Lucyna 
%A Tzioumis, A. K. 
%A Tingay, S. J. 
%A Macquart, Jean-Pierre 
%A McCulloch, P. M. 
%T Variability in GPS Sources
%J Publications of the Astronomical Society of Australia
%D 2003/06/04
%V 20
%N 1
%P 151-155
%K galaxies: active &#8212; quasars: general
%R https://doi.org/10.1071/AS03023
%U https://www.publish.csiro.au/paper/AS03023 
%X Flux density monitoring data at 2.3 and 8.4 GHz is presented for a sample of 33 southern hemisphere GPS sources, drawn from the 2.7 GHz Parkes survey. This monitoring data, together with VLBI monitoring data, shows that a small fraction of these sources, &#126;10&#37;, vary. Their variability falls into several categories: sources whose spectral classification is, at best, ephemeral on a timescale of years; sources with a stable GPS classification that vary, but retain their classification; and a small number of sources that exhibit interstellar scintillation, but that maintain a mean GPS spectrum. Existing data on GPS sources with higher frequency peaks, &#x2265;3 GHz, reveals that many such sources vary. However, the majority of these sources possess a GPS spectrum only during outbursts, and hence should perhaps be classified as ephemeral GPS sources. In addition, significant levels of circular polarisation have been found in a number of GPS sources, both amongst the variables and non-variables. Remarkable amongst these is PKS 1519&#8211;273, which possesses strong and variable circular polarisation, and which exhibits IDV in all Stokes parameters. 
