the SMA and ALMA, obtained by averaging the real and imaginary parts of of the complex visibilities in concentric annular bins, adopting the belt geometry derived in §\[sec:model\]. This view of the visibilities provides some insight into the image properties in Figure \[fig:cont\]. The shorter baselines from the SMA capture the steep rise in visibility amplitude at low spatial frequencies that are missed by ALMA, and thus sample better the emission responsible for the extended disk morphology. The visibilities from the two telescopes are consistent where they overlap at higher spatial frequencies that sample the small scale structure. The imaginary parts of visibilities are all consistent with zero, as expected for an axisymmetric structure.

Figure \[fig:vla\] shows a VLA 9 millimeter continuum image of the HR 8799 system, obtained with natural weighting and a $5\arcsec$ FWHM Gaussian taper, which gives a beam size of $6\farcs2 \times 5\farcs8$ and rms noise of 4.3 $\mu$Jy/beam. Significant emission is detected from an extended region centered on the star, but with a low peak signal-to-noise ratio of only $3-4$ per beam. No clear disk or belt morphology is evident in the emission at this sensitivity level. The emission peak near $(+10\arcsec,-10\arcsec)$ in the image 