Maps of the integrated intensity (color scale) between 5 and 15 km s^-1 of the ¹³CO (2  →  1, left) and C¹⁸O (2  →  1, right) lines observed at the IRAM-30 m telescope. Dashed white contours represent the integrated intensity of the H42α recombination line at 85.688 GHz (1 to 11 K km s^-1 in steps of 2 K km s^-1), tracing the H ii region. Squares represent the positions of the ionization front (IF) and the molecular peak (MP), whereas the triangles represent the points of the observed strip (dashed line) for ¹²CO (9  →  8), H₂O and NH₃ that are studied in this work. The infrared sources are indicated with black stars.