Impact of the integral constraint on the monopole correlation function in the Euclid Wide Survey. The curves with the different different symbols show the leading integral-constraint term ⟨ϵ²⟩, after 1, 3, and 6 years of observation respectively. The solid curves show the same quantity for year 6 observations, but when the integral constraint effect is derived from a model correlation function. The different colours show this quantity for the redshift intervals: 0.9 < z < 1.1, 1.1 < z < 1.3, 1.3 < z < 1.5, 1.5 < z < 1.8. The dotted curves delineate the expected 1σ statistical uncertainty on the monopole correlation function in the completed Euclid Wide Survey in the interval 1.1 < z < 1.3.