Left panel: H₂ surface density from ALMA CO(2–1) observations (12 m + 7 m + TP) convolved to 6.3″ resolution, with contours highlighting levels of (2, 6, 10) M_⊙ pc⁻². The dashed blue line is the ALMA field of view (where the primary beam response exceeds 20%). Central panel: H I surface density from the VLA at 6.3″ resolution (Mundell et al. 2004), with CO contours from the left panel in red. Right panel: the ratio of molecular-to-atomic gas surface densities derived from our CO(2–1) and H I observations (left and central panel) at 6.3″ resolution; CO contours as in the other two panels. In all maps north is up and east is left, with J2000.0 equatorial coordinates.