Summary of potential systematic uncertainties in the circular velocity curve at a vertical height of |z|< 3 kpc. We estimate systematic uncertainties arising from the neglected cross-term (see the red-dotted line), from varying the exponential scale length of the density profile (orange-dashed line), from passing from an exponential to a power law (blue-dashed line) with an index α = −2.25, and finally after splitting the sample into two parts (green-dotted line). The total systematic uncertainty (black-solid line) is at the 2% level up to R = 22.5 kpc, and then increases at larger radii.