Maps of the velocity-averaged C⁺ flux density (left), the 0.98mm continuum (middle) and the line-to-continuum ratio (right). The synthesized beam is 0.38′′ × 0.29′′ (lower left of each panel). In these maps, the cross marking the phase reference position, and the background greyscale image, are the same as in Fig. 1. Left panel: the C⁺ line flux density, in m Jybeam^-1, is averaged over the line full width of 940 km s^-1. Line contours are −3σ (dashed), + 3σ, and then going up in steps of 1σ = 0.24 m Jybeam^-1. The peak is 2.2 m Jybeam^-1, and the spatial integral is 9.9 m Jy. Middle panel: the dust continuum was integrated over 2GHz of line-free channels. Continuum contours are −3σ (dashed), + 3σ, and then going up in steps of 1σ = 0.19 m Jy beam^-1. The peak continuum emission is 1.4 m Jy beam^-1. The spatially-integrated continuum flux density is 4.6 m Jy. Right panel: the line-to-continuum ratio is roughly constant across the map; contour values are 1.0 (black) and 2.0 (red). In these units, the line-to-continuum ratio is dimensionless, and its typical value across the source is 1.5.