Emissions of the transitions in the 3 mm band. Left: spectral lines of the P point. Right: emission intensity contours from 50 to 90% in steps of 10% of the peak value (see Table 2). C₄H N = 9−8, J = 19/2−17/2 and C₄ H N = 9−8, J = 17/2−15/2 are summed up and shown as C₄H intensity contours. Red contours represent 3σ of integrated emissions. The symbols are the same as those in Fig. 1c. The green and pink filled triangles represent peak position of c-C₃H₂ J = 2−1 and HC₃N J = 10−9 emission, respectively.