Self-calibration on the delay calibrator. Top row: iterations of residual dTEC/DIFMAP self-calibration, starting with a point source and then using models generated from imaging the previous iteration. Bottom row: complex gain self-calibration, with three iterations on solution intervals of 1 h followed by a single complex gain iteration with a solution interval of 5 min. All plots are on the same colourscale with a log stretch to enhance the noise properties. The contours are set per row, starting at 10σ and increasing by , based on the final image in the row.