2D schematic diagram showing our explanation for the observed offset between the BLR and hot dust. The BLR (orange disc) is rotating, has a size of R_BLR, and its photocentre is marked as a red cross and is assumed to be the same as the position of the central BH. For simplicity, the hot dust (with a radius of R_dust) is assumed to have two sides: the left side being the fainter one and the right side being the brighter one. This causes the continuum photocentre (blue dot) to shift to the brighter side of the hot dust. The observed offset between the BLR and hot dust photocentres is labelled R_off.