Radio images at 60 MHz of the A399–A401 clusters pair. Left panel: low-resolution (75″, the beam size is indicated in the bottom left corner) image with compact sources and the σ_rms = 3 mJy beam⁻¹ produced with the parameters listed in Table 1. Right panel: same as the left panel, but after subtraction of the compact source. The contour levels (in white) start at 2σ_rms, 3σ_rms, and 5σ_rms and then increase to 20σ_rms with factors of 2. A negative contour at −3σ_rms is shown in red.