The effect on the [O III] flux distribution (reddish-purple contours) when the HST F547M optical continuum image (in grayscale) is multiplied by different factors before the subtraction from the FR533N image (narrow band filter covering [O III]). In the left, the continuum F547M was undersubtracted from [O III] – using a lower multiplicative factor – to avoid negative values are the center, with the inset showing a zoom-in in the central region. Notice that the smoothed [O III] contours follow the extended continuum distribution in this case. On the right, the continuum was subtracted using a larger factor that resulted in negative values at the center (upper map). For the final image, the [O III] image was interpolated to eliminate the negative values (lower map). To show that the spatial anticorrelation between CO and [O III] is visible in both maps, we added a single blueish-green contour, delineating the CO(2-1) flux distribution. In all zoom-in images, the F547M grayscale range is different maps to highlight the peak in the F547M image.