Summary of ALMA data of the H30α (top) and H39α (bottom) lines (see also Figs. A.2 and A.3). Left: integrated line spectrum obtained with ALMA (black lines) and with the IRAM-30 m antenna (gray histogram, CSC17). Middle: line emission maps integrated over the line profile (LSR velocity range [11:143] km s⁻¹). The level contours are (3σ)×1.5⁽ⁱ⁻¹⁾ Jy beam⁻¹, i =1,2,3… Right: first moment map. Contours going from V_LSR=45 to 115 km s⁻¹ by 5 km s⁻¹. The color bars indicate the V_LSR-colour relationship.