Rotation diagrams for three specific components and a population diagram for the fourth component identified in Sect. 3.2. Triangles indicate upper limits and error bars the 1σ standard deviation in the flux determination. The diagrams displayed are a) rotation diagram for the main,  − 10.5 km s^-1 velocity component at the “Centre” position (+3″,+3″). b) Population diagram for the redshifted,  − 5.2 km s^-1 velocity component at the “Centre” position (+3″,+3″); for this model asterisks indicate a best fit that includes optical depth effects and beam dilution (see Sect. 4.2), c) rotation diagram for the “NE Outflow” (+27″,+9″), d) rotation diagram for “Envelope” (+21″, − 3″).