Statistics of the attitude errors (top) and astrometric residuals (bottom) versus the frequency of the injected GW. Left: standard deviations of the errors or residuals. Right: averages of the errors or residuals. In the upper panels, A in ∆A is a placeholder for X, Y, or Z, the three axes of the Scanning Reference System (Sect. 3.1 of Lindegren et al. 2012). Similarly, in the lower panels, R is a placeholder for the residual along-scan (AL), across-scan in the preceding FoV (ACp), or across-scan in the following FoV (AC_f). The coloured bars show the range of statistics obtained in the five simulations for each frequency (see Sect. 4); for improved visibility the coloured lines connect the average statistics in the corresponding bars. The standard deviations of the residuals in AC_p and AC_f virtually coincide.