RA–Dec distribution of galaxies with reliable redshift (see text for details) in the VIPERS Public Release PDR-1 in W1 (top) and W4 (bottom) fields. The thick red line in each panel is the “field boundary” that we consider in this work. The VIMOS footprint with four quadrants is visible from the two single pointings at Dec ≲ − 5.08 deg in the W1 field at RA = 37.9 and RA = 30.4.