Middle: PdBI spectrum towards the emission peak. Top and bottom: integrated intensity maps of the most intense lines in the portion of spectrum between 219.5 GHz and 220.7 GHz. In all the panels the contours start and increases at steps of 3 × σ. Sigma and peak values in Jy/beam × km s^-1 are: 0.10, 2.47 (C¹⁸O 2–1); 0.12, 2.12 (HNCO 10₀–9₀); 0.21, 8.65 (SO 5₆–4₅); 0.22, 7.28 (¹³CO 2–1); 0.08, 2.20 (CH₃CN 12₄–11₄); 0.11, 1.04 (HNCO 10₃–9₃); 0.12, 2.13 (HNCO 10₂–9₂); 0.11, 1.18 (HCO 3_1,2–2_1,1); 0.14, 3.95 (E-CH₃OH 8₀–7₁); 0.13, 2.5 (CH₃CN 12₅–11₅). Filled triangles indicate the water masers as observed with the NRAO Very Large Array (Aina Palau, priv. comm.). The masers trace the direction of the youngest outflow (Fuente et al. 2001) that is also clearly seen in the SO and ¹³CO images. The (0, 0) position is the phase center of the interferometric observations: , (J2000).