Left panel: 323 MHz GMRT full–resolution (11.8′′× 7.8′′, p.a. 16.9°) image of the 19′× 19′ area around the cluster M 0520. Contours are spaced by a factor of two and start at ±3σ = 0.33 mJy/b (negative contours are dashed). The dashed circle indicates the central region of 1 Mpc radius around the cluster M 0520. Right panel: zoom in of the area around the diffuse elongated source; radio contours (same as in left panel) are overlaid on the DSS2 optical red image. The black circles show position of the three galaxies from DSS catalog, which are likely optical counterparts of radio sources S1 and S2.