Four examples of Faraday depth spectra of different sources. For each, the source’s Faraday spectrum and foreground Faraday spectrum are shown in black and grey respectively, the 8-sigma (noise) level is marked in a horizontal dotted line, and the excluded Faraday depth range around the instrumental leakage is boundedby vertical dotted lines. The four spectra were selected to show examples of different phenomena. a) a typical detection that passed all of the tests in Sect. 2.4, with a clear bright source at +12 rad m⁻²; b) a non-detection with bright foreground (both on-source and off-source) at +3 rad m⁻², showing the need to consider the foreground emission when identifying sources; c) a polarized candidate (which failed the tests) at +3 rad m⁻², which can be seen in the full 3D cube to be a local enhancement in the foreground emission; d) a polarized source at +17 rad m⁻² that passedall tests, with an artificial “mirrored” peak at −18 rad m⁻² (an artifact discussed in Sect. 2.4).