Observed spectral lines (shaded grey) and Gaussian fit profiles (black lines) towards a 37.5′′  ×  37.5′′ grid centred at RA = 19:10:13.4; Dec: 09:06:14. The X-axis is velocity relative to the line rest frequency (km s^-1); the Y-axis is T_mb (K). HCN J = 3−2 (top); HCN J = 4−3 (middle); HCO⁺ J = 4−3 (bottom). The dashed vertical line on each plot is at the expected source velocity of 7 km s^-1.