Azimuthally averaged radial profiles of the integrated flux for the 7 hyperfine (hf) components of C¹⁴N, four of which are optically thin, the remaining three being optically thick (Fig. 2). The average of the 7 hf components is shown in red. The black line shows the result of a sharp inner-ring model plus Gaussian decrease outwards, convolved by the synthesized beam. The unconvolved ring has a radius of 0.7′′ or 42 AU, and a full-width at half-maximum of 54 AU (at a distance of 59.5 ± 0.9 pc).