Left: ¹²CO contours on a WFPC2 image zoomed in on the central region. Centre: ¹³CO contours on WFPC2 image. Both ¹²CO and ¹³CO contours are 40% of peak flux  ×  (1, 1.5, 2, 2.25). For ¹³CO the first contour starts at 2.5σ, for ¹²CO the first contour starts at 24σ. Right: line ratio map where the greyscale ranges from light (ℛ = 10) to dark (ℛ = 60). Both limits and real values in greys (same scale), and the area where there are actual measures overlaid with contours (yellow). Contours are ratios ℛ = 15, 25, 35, 45. Limits are at the 3σ¹³CO detection threshold. Please note the small pixel-size (0''̣5) of the ¹²CO and ¹³CO maps which may give the impression that there is structure beyond the actual angular resolution of the ¹²CO and ¹³CO maps.