Angular velocity curve for the disk of NGC 253 from Arnaboldi et al. (1995): Ω(R) (solid black curve) and the curves relative to Ω(R) − K(R)/2 (short-dashed red line), Ω(R) + K(R)/2 (long-dashed blue line) and Ω(R) − K(R)/4 (long-dashed-point magenta line). The horizontal line corresponds to the value of the bar pattern speed Ω_b ≃ 61.3 km s^-1/kpc. The two vertical segments correspond to the ILR (at R ~ 0.33 kpc) and OLR (at R ~ 4.9 kpc) radii. The two dotted vertical segments correspond to the range of radii where the UHR lies at R ~ 1.3 kpc. The two vertical arrows indicates the lower and upper limit for the Ω_b.