Distribution on the sky of the galaxies with measured redshifts in the VIPERS PDR-1 catalogue within the W1 and W4 fields (blue points). The pattern described by the gaps separating the VIMOS quadrants, as well as the areas not covered by the PDR-1, are clearly visible. Superimposed to the spectroscopic data, we also plot for illustrative purposes the projection of a subset of the spherical cells used to estimate the variance (regular grid on the left) with the typical motif used to estimate the 2-point correlation function of the smoothed density field ξ_g,R(r) (right). The spheres have a radius of R = 5   h^-1   Mpc, and the chosen set is placed at redshift z = 0.66. Note that the distance between the centres of 2 opposite spheres in the motif is exactly equal to the chosen correlation scale r (we show here the case r = 3R). Red circles correspond to spheres that have been rejected in the clustering analysis because they are heavily affected by the survey mask (see discussion in Sect. 5.2.)