Gas rotation curve of NGC 5248, spanning the inner 4 kpc (left) and the entire disk out to 24 kpc (right). The rotation curve is based on our CO(2−1) (squares), as well as BIMA SONG CO(1−0) (diamonds) and VLA HI (triangles) data, giving both high spatial resolution and large radial coverage. A circular velocity curve is fit using Eq. (1), solid line. Frequency curves of Ω (solid, blue), Ω + κ/2, Ω − κ/2 (both dash-dot, red) and Ω − κ/4 (dashed, green) are also presented. The bottom panels show the difference between circular velocity model curve and ROTCUR derived rotation curve. (See text for further details.)