we summarize the main conclusions.

Observations {#sec:obs}
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Submillimeter Array
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We observed the HR 8799 system with the SMA on Mauna Kea, Hawaii, at a wavelength near 1.3 millimeters in the subcompact configuration that provides projected baselines as short as 6 meters. Table \[tab:sma\] provides a log of these observations, including the observing dates, weather conditions, number of operational antennas, and the useable hour angle range. In this close-packed antenna configuration, the lower elevation limit for observations is $33\degr$, to prevent antenna collisions. The phase center was set at $\alpha=23^\text{h}07^\text{m}28.72$, $\delta=+21\degr08\arcmin03\farcs3$ (J2000), i.e. the J2000 star position uncorrected for interim proper motion. Two units of the SWARM digital correlator, still under construction at the time, were available; together these spanned bands $\pm(4-12)$ GHz from the LO frequency of 225.5 GHz, with uniform channel spacing 140 kHz ($\sim$0.18 km s$^{-1}$). This setup provided a total of 16 GHz of continuum bandwidth, as well as simultaneous coverage of the $^{12}$CO J=2-1 (230.53800 GHz) and $^{13}$CO J=2-1 (220.39868 GHz) spectral lines in the upper and lower sidebands, respectively. The primary beam FWHM size of the 6-meter diameter array antennas of $55\arcsec (\nu/230~{\rm GHz})$ set the useable field of view.

The basic observing 