Stack of quasar spectra with a sightline within 3 × R₂₀₀ of the centre of a cluster, and with known MgII absorbers from the MgII absorption catalogue of Anand et al. (2021) satisfying |dv|< 2000 km s⁻¹. The figures display the normalised flux in velocity space. The first dashed line at −100 km s⁻¹ is fixed at the location of the minimum flux within [−2000:2000] km s⁻¹ of the redshift of the known MgII absorber. The second dashed line is placed at +750 km s⁻¹ from the first dashed line, which corresponds to the separation of the two MgII lines in the doublet. The solid vertical lines are fixed at −500 km s⁻¹ from 2976 and +500 km s⁻¹ from 2803 line. The green line shows the fitted continuum used for the EW measurement.