Shaded regions illustrate the allowed range of circular velocity when the anisotropy parameter is varied from β = 0 to β = 0.5 for a fixed tracer density γ _tr = 4 (bottom left toward top right) and when the tracer density is varied from γ _tr = 3.5 to γ _tr = 4.5 for a fixed β = 0.4 (top left toward bottom right), same as in Figure  2. Thick dashed line shows a representative fit for an NFW halo model (see the text for details). Independent constraints at 8, 50, 60, and 100 kpc are from McMillan & Binney (2010), Wilkinson & Evans (1999), Xue et al. (2008), and Watkins et al. (2010), respectively.