Square root of the CRLB in mas for a moving source observed with a two-dimensional array detector as a function of detector pixel size Δx in arcseconds. The figure is divided into three sub-figures, each one corresponding to a specific orientation of the source drift with respect of the detector-array frame. Within each sub-figure, each line corresponds to two different values of decentering along X and Y axis between − 0.46 and 0 pixel. The parameter values are L = 3.0′′, FWHM = 1.0′′, e⁻, D = 0e⁻/pix, RON = 5e⁻/pix, and b = 6000e⁻/arcsec².