Answer 6

The visibility amplitudes for the phase ref are almost constant as a function of projected baseline length (uv distance in metres), showing that it is point-like to e-MERLIN with a resolution of 50 mas.

The amplitudes are noisiest out to about 130 km because these are the Defford baselines and that telescope is least sensitive. There is a little data with anomalously low amplitudes but because we know that the target is bright we won't worry about that for now.

The target has higher amplitudes on the shorter baselines, showing that it has structure on scales larger than 50 mas, and it has a complex strucuture on the long baselines.