Critical orbital velocities vs. mass: for an equal-mass binary of mass M at z = 0.6, a plot of orbital velocity vs. mass. The two dotted upward-sloping lines are the velocities associated with 1 year (bottom) and 1 day (top) orbital periods; a 1 year survey with 1 day cadence will be roughly sensitive to this range of time periods. The downward-sloping blue line shows the minimum velocity β _c , above which the jet is bright enough to be seen at z = 0.6, assuming = 0.002 and F _min = 1 mJy; this curve depends strongly on source distance, efficiency, and survey flux limit. Finally, the thick green line is β _*, the velocity at which the binary separates from the circumbinary disk (Equation (9)). The shaded region is bounded by β _± and corresponds to the range of velocities where a binary is both isolated and detectable as a periodic source. The time Δ T a binary spends evolving through this region is Δ T = T(β ₊) − T(β ₋) for T given by Equation (8).