Maps of integrated intensity (in the range 5–15   km   s^-1) for CCH (262.004  GHz) and c-C₃H₂ (217.822  GHz) obtained with the EMIR receivers. Black contours are the C¹⁸O line shown in Fig. 1. White triangles and squares represent the single positions studied in this paper. White contours in the left panel represent the c-C₃H₂ line integrated intensities (in the range 5–15  km   s^-1) starting from 0.6  km   s^-1 and in linear steps of 0.2  km   s^-1.