Astrometric accuracy as a function of angular separation between phase calibrator source and target. This is a reproduction of Fig. 3 in Chatterjee et al. (2004) (referred to as C04 here) to which we added data from our observations (open and filled stars). Open symbols denote the median scatter about the average position of the primary phase calibrator obtained from calibrating its visibilities with solutions from the secondary calibrator. Filled symbols show the median scatter of the observed positions about the best-fit model for proper motion and parallax. The 1.6GHz data (squares) are taken from Chatterjee et al. (2001) and Vlemmings et al. (2003), while the previous 5GHz data (circles) are taken from Chatterjee et al. (2004). The solid line is a weighted least-squares power-law fit to all 5GHz data points. The almost linear relationship between astrometric error and calibrator throw seems to break down beyond an angular separation of more than about four degrees.