The basic conclusion is that we do indeed see a good correlation between the water line measurements and astronomical phase. While the results from a single track are highlighted here, there have been many tracks from the past observing season where good correlations are observed. Coherence corrections are relatively easy, and many tracks in the past season can be improved in this manner using the WLM measurements. Applying full phase corrections is still in the experimental stage, but the results presented here are extremely encouraging that this technique can be successful.

The main goal of our future efforts is to improve the residual phase RMS still further. The current phase residuals are between 100 and 200 microns, and the goal is to achieve 50 micron rms. The main source of of error currently is the noise in the water line boxes themselves. We currently in the process of cooling down the water line boxes, which should improve the system temperature by a factor of 3-4, and the phase residuals should decrease by the same factor.