${\mathrm{\Omega }}_{\mathrm{b}\mathrm{a}\mathrm{r}}$ in NGC 5597 from VLA HI 21 cm Observations

We report Very Large Array B-configuration observations of the atomic hydrogen 21 cm line emission from the barred disk galaxy NGC 5597 at an angular resolution of 7.1" x 4.2". Using the resonance method, and assuming the ratio of the corotation radius to the semi-major axis of the stellar bar is unity ($\mathcal{R}\equiv R_{\mathrm{C}\mathrm{R}}\mathrm{/}{a}_{\mathrm{b}\mathrm{a}\mathrm{r}}=1$), we estimate the angular pattern speed of the stellar bar to be, ${\mathrm{\Omega }}_{\mathrm{b}\mathrm{a}\mathrm{r}}\sim 15.3$ km s${}^{-1}$ kpc${}^{-1}$. This constant value for ${\mathrm{\Omega }}_{\mathrm{b}\mathrm{a}\mathrm{r}}$ crosses ${\mathrm{\Omega }}_{\mathrm{g}\mathrm{a}\mathrm{s}}+\kappa (R)\mathrm{/}4$ at a distance $\sim 6.73$ kpc which would correspond to the spatial location of the north spiral structure near an outer m=4 resonance. This value of ${\mathrm{\Omega }}_{\mathrm{b}\mathrm{a}\mathrm{r}}$ is similar to the values estimated for other bright nearby barred galaxies that exhibit circumnuclear rings (near ILR) or outer rings (near OLR).