with the extended halo. The relatively large radial extent of this belt coupled with the young age of the system supports “planet-stirring” models to produce the collisional debris [@moor15].

Millimeter emission selectively reveals the large dust grains less affected by radiative forces that therefore trace best the distribution of dust-producing planetesimals within debris disks [@wyatt06; @wilner11]. Single dish observations of HR 8799 from the CSO at $350~\mu$m ($9''$ beam) resolved emission from the cold belt around the star, with a tentative offset asymmetry [@patience11]. This asymmetry was not confirmed by observations with higher signal-to-noise ratio from the JCMT at 450 $\mu$m and 850 $\mu$m ($8''$ and $13''$ beam, respectively) [@holland17]. Millimeter imaging of the disk at much higher angular resolution has proven challenging on account of its low surface brightness. @hughes11 made the first millimeter interferometric detection of the disk, using the Submillimeter Array (SMA) at 870 $\mu$m, consistent with the presence of a broad belt ($\Delta R/R > 1$) of inner radius $\sim150$ AU. Recently, [@booth16] used the Atacama Large Millimeter/submillimeter Array (ALMA) to image the HR 8799 system at 1.3 mm at much higher sensitivity, although these observations recovered only a small fraction of the total disk emission. 