Residual aberrations in differential OPD maps obtained for the simulated realistic observation of a target at declination δ = −37° and at hour angles from −0.62 h to +0.53 h. In this sequence the UT3 telescope was tracking inside the dome, and the derotator and ADCs were tracking as in a real observation. The OPD maps are subtracted by quasi-symmetric pairs around meridian passage, that is for almost identical orientations of the derotator. The red curves show the contribution for the estimated fast internal turbulence over 20 s timescales for the temporal sequences presented in Sect. 2.2.