Potential detectability of the trend toward the universal EVPA at the horizon in M87*. Top left: a time-averaged 230 GHz image of a spin a_* = 0.9 MAD GRMHD simulation of M87* viewed at an inclination θ_o = 163 deg and rotated so the spin axis points left. Top center: an idealized image reconstruction of the GRMHD image using simulated data sampled on EHT+BHEX baselines. Top right: the (u, v) coverage of the EHT+BHEX array used in the image reconstruction, with 230 GHz ground–ground baselines shown in blue and ground–space baselines shown in yellow. Array baselines at 86 and 320 GHz are indicated in gray. Bottom: values of ∠β₂ as a function of image impact parameter extracted from the top row GRMHD image (solid black line), values extracted from the same image blurred with a 3 μas FWHM Gaussian kernel representing half of the BHEX nominal beam at 230 GHz (dashed black line), and values extracted from the reconstructed image (green squares). The 2σ error bars on the reconstruction data points were derived assuming a uniform rms noise level of 10⁸ K, or approximately 1% of the peak total intensity.