Simulating the automated detection by PS1+MOPS of smaller impactors is difficult. At the current time MOPS operates by linking together tracklets on three nights taken over the course of 10 days. With typical impact velocities of 15 km/s the best case scenario requires that PS1+MOPS first detect the object at a distance of 13 106 km (approximately 10 days before impact). At PS1’s assumed limiting magnitude of V = 22.7 this requires that the object be >3 m in diameter. Even if this situation were to unfold, variations in the object’s apparent position and velocity on the sky due to the topocentric motion of the observatory would likely render the object difficult to link within the MOPS (though we have not yet studied this scenario in detail). Instead, we consider the possibility that PS1 will detect an impacting asteroid prior to impact but on too few nights to determine a pre-impact orbit.