This figure highlights the before/after images on 0309+411 using the data in the second half the track where the phase stability was the worst. Before applying the water line corrections, the image has a FWHM of about 2 arcseconds, which is significantly larger than the beam size shown in the lower right. After applying the water line corrections, the image is only a couple of tenths of an arcsecond larger than the theoretical beam size, and the peak amplitude has increased by a factor of 2.6.