This figure shows that the correlation between astronomical phase and the water line measurements can hold over entire tracks. Plotted here are the observed WLM temperatures (top panel) and the observed astronomical phase on 3C84 (middle panel) for a single baseline. The x-axis is the sample number of the astronomy data, and essentially represents time (over a 5 hour time period) through the track. The projected baseline length for these data is about 400 meters.

Before applying any water line corrections, the astronomical phase RMS is 66 degrees. Note however, that the phase RMS increased near the end of the track as the weather conditions deteriorated. The bottom panel shows the phase residuals after essentially subtracting the WLM measurements from the astronomical phases. The phase residuals have a RMS of 30 degrees, which represents over a factor of 2 improvement from the uncorrected phases. Further, the phase RMS is relatively constant over the track, even during the time period when the weather was relatively poor.