2001). For this range, the probability for the massive–halo model varies over the range $0.059>p>0.004$. Therefore, for a spread of values of $c$ within the quoted range, the probability for the massive–halo model remains low.

3.  The results are rather insensitive to small variations of the exponential scale radius, $R_0$, and the spatial cut $r_{lim}$. This is because for variations in either parameter we have to adjust the parameter $\beta$ such that the average projected radius at which the rotation velocity is measured matches that of the data. We confirmed that for smaller $R_0$ the measured $\alpha(obs)$ is slightly higher, and [*vice versa*]{}. This is as expected because for smaller $R_0$ the light is more concentrated, so after convolution with the seeing the luminosity–weighted rotation velocity at any radius receives proportionally more light originating at smaller radius, where the rotation velocity is lower.

4.  We also checked the sensitivity of the result to the value of the spectral cut $V_{min}$. Our analysis uses the spectral cuts applied to the data $V_{min}=50$[kms$^{-1}$]{} and $V_{min}=25$[kms$^{-1}$]{} for the NIRSPEC and ISAAC datasets respectively, and we have taken these at face value. Nevertheless it is interesting to check how the conclusions would have differed, 