Examples of 383 MHz uGMRT images of A21-G114.9 where the bridge visibilities are injected, as a function-integrated flux density, f. X-ray ROSAT contours are shown in yellow and the location of the X-ray peak is marked with yellow crosses. In particular, we show the different contribution of the injected bridge emission when increasing its flux density, from f = 50 mJy to f = 260 mJy. The visibilities are injected inside a 2D model Gaussian (dashed blue ellipse) with a semi-major axis of 12′ (∼2.5 Mpc) and a semi-minor axis of 5′ (∼500 kpc). We note how in the first two top panels the bridge emission is not significantly detected, while approaching the two values found for the upper limit on the flux density (bottom panels) the emission is continuous and detected over 2σ_rms. Contour levels are drawn from 2σ_rms (in purple) to 5σ_rms (in black). A negative contour level at −3σ_rms is shown in red.