in each coordinate ($\sim3\sigma$). We do not attach any significance to this shift. If we aligned the jet positions, the proper motions listed in Table 2 would change by about 2 mas yr$^{-1}$. This amount is insignificant and does not change any of our conclusions.

We note that the faint features that appear marginally detected at the 4-$\sigma$ level in the images of the individual epochs (for example, some faint structures to the west of the central source in the 2006.42 image), do not appear in the difference image, since this is about $\sqrt{2}$ noisier than the individual images.

As already discussed by Rodríguez et al. (2005), the lobes first observed by Garay et al. (2003) break into several components. A more careful examination of the 2003 map in conjunction with the 2006 map shows that there are two other components present in the northern lobe (components N-4 and N-5; see Table 1 and Figure 2), as well as two additional field sources (sources D and E, see Table 1).

In this section we will discuss the sources individually when new information was found, and in the following section we focus on the search for variability and proper motions. Most 