e-MERLIN images of the calibrator source, J1525+1107. Left: At 1.5-GHz. The peak intensity is 420 mJy beam⁻¹. The lowest positive contour is drawn at 1.1 mJy beam⁻¹, which corresponds to a 7σ image noise level. The FWHM size of the restoring beam is 321 mas × 144 mas and its major axis is oriented at a position angle of 21°. Right: 5-GHz. The peak intensity is 274 mJy beam⁻¹. The lowest positive contour is drawn at 0.75 mJy beam⁻¹, which corresponds to a 7σ image noise level. The restoring beam is shown in the lower left corner, its FWHM size is 91 mas × 44 mas, and its major axis is oriented at a position angle of 24°. The two image cutouts have the same size. To illustrate that the 1.5-GHz peak corresponds to the secondary rather than the primary brightness peak at 5 GHz, the images are displaced by 110 mas with respect to each other in the declination direction.