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tokens: varies less with MC sampling rate than the ejected mass (see below). Figure 4 also shows why it is so difficult to accurately estimate the amount of unbound material in a simulation: the steepness of the Lorentz factor distributions implies that a very small error in the estimated location of the boundary between bound and unbound material has large effects on the predicted mass of unbound material. The second, more minor difference is that the cutoff of the velocity distribution is slightly lower in both MC simulations ( v max ∼ 0.5) than with M1 ( v max ∼ 0.55). We can compare these results to Sekiguchi et al. ( 2016 ), who performed a longer simulation with M1 transport, the same equation of state, and slightly more symmetric masses. They find 0.005 M ⊙ of ejecta with and , and a Y e distribution fairly similar to those obtained with our M1 code—results that are broadly consistent if the higher mass asymmetry led to the ejection of an additional 0.003 M ⊙ of neutron-rich material. The properties of neutrinos escaping the system are summarized in Figure 5 . After the first 2 ms, the average energy of neutrinos and the ν e and luminosities in the M1 and MC simulations agree within ∼20%. The ν x luminosity, on the other hand, is nearly twice as large in the MC simulation. Differences between the two MC simulations are negligible compared to differences between MC and M1. The luminosity of heavy-lepton neutrinos is one of the most uncertain observable in our M1 scheme, because a large region close to the neutron star surface has negligible κ a but large κ s . In that region, neutrinos are trapped, but out of thermal equilibrium with the fluid. As the energy closure is the most ad-hoc part of our M1 algorithm, and the diffusion rate of neutrinos strongly depends on the choice of energy spectrum, this is a particularly difficult situation. The MC scheme has no particular reason to perform poorly in that regime: while it corrects large absorption opacities, its treatment of high-scattering regions is better motivated than that of the gray M1 scheme. Nevertheless, it may be premature to assume that the MC scheme provides the better answer, as the two schemes may be impacted in different ways by the grid resolution. In Sekiguchi et al. ( 2016 ), neutrino luminosities reach values similar to those measured here within ∼5 ms, before decreasing on the cooling timescale of the remnant. Figure 5. Left panel: angular distribution of the electron antineutrinos leaving the grid (3–5) ms after merger; θ is the angle with respect to the angular momentum vector, i.e., polar neutrinos are on the left, equatorial neutrinos on the right, and each bin covers the same surface area. Middle panel: neutrino luminosity in the high-resolution MC simulation and the M1 simulation. Right panel: average (number-weighted) energy of neutrinos leaving the computational grid in the same simulations. The angular distribution of neutrinos shows clearer differences between