Linear polarisation maps of HCG15 as seen by ASKAP at 943 MHz (top) and by MeerKAT at 2.41 GHz (bottom), both at a resolution of 20 arcsec. Colourmaps show the linearly-polarised intensity (left), the fractional polarisation (centre) and the residual rotation measure (RRM; right). Vectors denote the orientation of the magnetic field, scaled according to the magnitude of the fractional polarisation. Contours show radio continuum surface brightness as per Fig. 2. The fractional polarisation, polarisation angle and RRM are blanked below a threshold of 4σ_P where σ_P = 28 μJy beam⁻¹ for ASKAP and 3 μJy beam⁻¹ for MeerKAT.