Channel maps for the CO isotopologs, N-bearing species, HCO⁺ and H₂CO. The velocity range is divided in three velocity bins with respect to the systemic velocity of  −5.8 km   s^-1:  [−1.5, + 1.5] km   s^-1 is shown in gray scale stretched between 0.7 K   km   s^-1 (white) and the maximum intensity in the central channel (black); all emission at relative velocities below  −1.5 km   s^-1 is shown in blue contours, and all emission at relative velocities above  +1.5 km   s^-1 in red contours. The lowest contour level is manually fine-tuned to emphasize velocity structure in each case without showing too much noise. Consecutive contour levels are drawn in steps of 10% of the maximum intensity in the brightest channel. Lowest contours: 15.0 K   km   s^-1 for CO, 5.0 K   km   s^-1 for ¹³CO, 0.8 K   km   s^-1 for C¹⁷O, 0.35 K   km   s^-1 for HCN and HNC, 0.4 K   km   s^-1 for N₂H⁺, 0.8 K   km   s^-1 for CN 3_5/2–2_3/2, 1.0 K   km   s^-1 for CN 3_7/2–2_5/2, and 0.8, 0.4 and 0.3 K   km   s^-1 for the three respective H₂CO transitions. The FWHM of the telescope beam is indicated in the top left corner of each panel.