Top panel: possible model for the rotation curve in the central kiloparsec of NGC 4948, built from its various components, that is, the bulge, disc of stars and gas, black hole, and dark matter. This latter contributes negligibly but it is required to explain a flat rotation curve in the outer parts (see text). Bottom panel: precessing frequency of elongated orbits, Ω − κ/2, used to model the orbits in the inner region of NGC 4968. The red line indicates the pattern speed of the bar (e.g. Buta & Combes 1996).