UV-space PV diagram of C¹⁸O. v_lsr = 3.7 km s^-1 . The red points indicate the redshifted (v > 5.0 km s^-1) emission. The velocity range covered in this diagram is indicated in Fig. 3. Blueshifted emission (v < 2.8 km s^-1) is not included in the diagram since it is strongly affected by foreground emission (see Fig. 3 and Sect. 3.2). The points are fit with a power law of the form v = aRⁿ. The solid line shows the fit to the high-velocity points (v > 5.7 km s^-1), while the dashed line shows the fit to the low-velocity points (v < 5.7 km s^-1). This suggests that the pure Keplerian disk extends to a radius of 50 AU.