Residuals obtained from the differences between the maps in Fig. 2, as indicated on top of each frame. From left to right and up to down, the rms noise in μJy beam^-1 is 28, 28, 29.6, 28, 29, and 29, respectively. Contour levels are given in units of rms noise at the bottom of each panel. All residuals tend to be well aligned with the jet position angle. The map corresponding to the 2000 epoch has not been used because 1E 1740.7−2942 was not at the phase center and the primary beam corrections would then render the difference maps meaningless.