Frequency curves for NGC 2523 and NGC 4245. The horizontal lines correspond to the inclination‐corrected ﹩\Omega _{P}﹩ of ﹩6.5\pm 1.5﹩ km s⁻¹ arcsec⁻¹ for NGC 2523 and ﹩4.6\pm 1.9﹩ km s⁻¹ arcsec⁻¹ for NGC 4245. The short vertical lines correspond to the error range in ﹩\Omega _{P}﹩. They are placed at the estimated bar (left) and inner ring (right) radii for NGC 2523 and the nuclear ring (left), bar (middle), and inner ring (right) radii for NGC 4245. The horizontal lines intersect curves corresponding to (left to right) ﹩\Omega -\kappa / 2﹩, ﹩\Omega -\kappa / 4﹩, Ω, ﹩\Omega +\kappa / 4﹩, and ﹩\Omega +\kappa / 2﹩; Ω is the circular angular velocity and κ is the epicyclic frequency. The corotation radius is where ﹩\Omega =\Omega _{P}﹩.