Ellipse-fitting toward the arms and rings detected in the MWISP ¹²CO images. Panels (a) and (b) show the intensity image integrated within [−13, −11] km s⁻¹ (blue range). Contours start from 2 (left panel) and 4 K km s⁻¹ (right panel), respectively, and increase in steps of 2 K km s⁻¹ (where 1 σ∼ 0.3 K km s⁻¹). The dashed blue (partial) ellipses show the fitted results toward the arms and rings. Panels (c) and (d) show similar results, but integrated within [−10, −8] km s⁻¹ (red range). Contours start from 2 K km s⁻¹ (left panel) and 4 K km s⁻¹ (right panel), and increase in steps of 2 K km s⁻¹. The yellow “+” symbol in each panel shows the geometric center of various ellipses (l =182﹩\mathop{.}\limits^{^\circ }﹩355 and b = −0﹩\mathop{.}\limits^{^\circ }﹩630). The parameters (minor and major axes) of the fitted ellipses for the rings are listed. For comparison, the center defined from the surface density image is shown as a yellow “×” symbol in each panel (l =182﹩\mathop{.}\limits^{^\circ }﹩42 and b = −0﹩\mathop{.}\limits^{^\circ }﹩70). In the red velocity range, the dashed pink square shows the position of IRAS 05480+2545, an active star-forming region.