Distribution of the $Q_{5\sigma }^{\text{hull}}$ parameter as a function of the area of emission above 5σ. The horizontal dashed line marks the $Q_{5\sigma }^{\text{hull}}\sim 0.8$ threshold identified in Fig. 15 to distinguish roughly circular areas of emission from more complex morphologies. The vertical dashed line indicates the maximum area of the beam for all fields, showing that a significant fraction of approximately circular emission areas (above the horizontal line) have areas much larger than the beam.