Calibration of the Lockman Hole (upper panel) and Boötes (lower panel) flux density scales. The default DDF-PIPELINE scale is set to unity and marked with a blue cross. The flux density ratios with respect to other surveys in the literature and their errors are shown in different colours and the fitting line is shown as a red dashed line. The inset shows a zoom view of the area close to the 144 MHz frequency of the observation.