Capabilities of the MGCLS data. Panel A: brightness cutouts from the MCXC J0027.3−5015 field, showing MeerKAT’s instantaneous sensitivity to a range of angular scales. From left to right: full-resolution (7.4″ × 7.0″), convolved 25″ resolution, and filtered ‘diffuse emission’ at 25″ resolution. The synthesised beam is shown in grey in the lower left corner of each image. The colour scale is in square root scaling in each case, with a minimum and maximum brightness of −10 and 600 μJy beam⁻¹ (left), 6 and 400 μJy beam⁻¹ (middle), and 25 and 150 μJy beam⁻¹ (right), respectively. See Sect. 4.3.1 for further details. Panel B: example of an in-band spectral index map of a bent tailed source in the MCXC J0431.4−6126 field, with total intensity coloured by spectral index. The host galaxy, 2MASX J04302197−6132001, is coincident with the radio core (seen in cyan). The colour scale indicates the spectral index, and the brightness gradient of the colour bar indicates intensity, with a burned-out maximum of 10 mJy beam⁻¹. Regions where the S/N was too low to determine a spectral index have been left white. The synthesised beam (7.1″ × 6.7″) is shown by the grey ellipse in the lower left corner. Panel C: example of an RM map of a complex MGCLS source in the Abell 3667 field. Contours are Stokes-I intensity with levels of (5, 10, 20, 40, 60, 80, 100) × σ, where σ = 6.7 μJy beam⁻¹. To avoid including spurious RM values, pixels with Stokes-I intensity below 8σ have been masked. Panel D: H I velocity map of Minkowski’s object in Abell 194, at a resolution of 19″ × 15″ (beam shown at the top left). Contours show the integrated H I flux density at levels of (0.35, 0.7, 1.4, 2.5) mJy beam⁻¹. Colours indicate the relative velocity from −22 km s⁻¹ (blue) to +22 km s⁻¹ (red) from the central velocity of 5553 km s⁻¹.