Measures of strength of compact structure on baselines to ST001 from individual international stations, plotted with different colour points. The ordinate on each axis is the scatter in difference in phase solutions between L and R polarizations, which is independent of the atmospheric phase rotation and depends only on the signal-to-noise of structure on that baseline. On the left, the abscissa is the scatter in difference in delay solution between L and R, and on the right it is the absolute delay scatter on the L polarization. The diagram on the left shows the regions in which we consider calibrators to be good (P), marginal (S), or not enough correlated flux for calibration (X). Areas marked D are usually those with some problem with the data.