Left: visibility amplitudes for simulated observations of M87* (top) and Sgr A* (bottom) at observing wavelengths of 1.3 mm (gray) and 0.87 mm (red). The synthetic data have been generated using the ngehtsim package assuming array specifications appropriate for the phase 2 ngEHT array from Doeleman et al. (2023), including simultaneous dual-band observations, the use of the FPT calibration technique, and 16 GHz of bandwidth at both frequencies. Data points are colored by their S/N on an integration time of 5 minutes, and data points with S/N < 3 have been flagged. Right: images produced from GRMHD simulations of the M87* (top two panels; Event Horizon Telescope Collaboration et al. 2019e) and Sgr A* (bottom two panels; Event Horizon Telescope Collaboration et al. 2022b) accretion flows, used to generate the synthetic data shown in the left panels. Both simulations have been ray-traced at observing wavelengths of 1.3 mm (gray) and 0.87 mm (red), and the frequency-dependent effects of interstellar scattering have been applied to the Sgr A* images (Johnson 2016; Johnson et al. 2018).