(a) Offset of the isophotal center with respect to the SBH as measured on different instruments at different frequencies. Each photocenter is centered on an ellipse whose axes represent the IQR of the isophote centers data set used to derive the photocenter. Error bars represent the error on the offset. The diamond marks the origin of the reference frame (SBH position). (b) As in panel (a) for the galaxies showing a double-nuclear point source. The offset of the fainter nuclear point source with respect to the SBH is marked with a diamond and the label NPS2.