Galaxy luminosity density map, generated from optical photometric data (galaxies with r-band magnitudes R_c < 22 and redshifts in the range 0.019–0.079), revealing a north–south extension. The red cross indicates the BCG, the yellow triangle marks the X-ray peak (RA = 206.86°, Dec = − 32.86°), the purple star shows the position of A3572, the green rectangles denote the FoV of EP-FXT, and the black contours show the X-ray isophotes.