Band 7 moment 0 maps (of emission only) of three ground-state lines overlayed on the 343 GHz continuum contours (0.74 × (1, 2, 4, 8) mJy). We note that the white “hole” in the centre is due to absorption and that absorption affects the line profiles out to at least 50% of the continuum. Some of the “missing” emission in structures is also due to line self-absorption. The cross marks the position of the continuum peak. Left panel: HCN 4–3 where colours range from 0 to 0.7 Jy km s⁻¹ beam⁻¹; Centre panel: HC¹⁵N 4–3 with colours ranging from 0 to 0.18 Jy km s⁻¹ beam⁻¹; Right panel: CS 7–6 with colours ranging from 0 to 0.23 Jy km s⁻¹ beam⁻¹.