Comparison of the continuum emission throughout the various observed epochs. This has been approximated with the Brγ-filter images, except for the runs of July 2000 and August 2006 where broad-band K images corrected for line emission have been used. The flux levels have been adjusted so that the mean of the counts of stars 2 and 4 is the same in all frames. The dimming of the northern lobe (especially region N1) and the simultaneous brightening of the southern lobe in July 2003 are evident.