low spin-down age.

The first step in picking a globular cluster is a figure of merit based on that for directed searches for supernova remnants [@Wette2008], an indirect upper limit on gravitational wave strain based on energy conservation and the age of the object. Here the inverse of the object age is replaced by the interaction rate of the globular cluster, which scales like density$^{(3/2)}$ times core radius$^{2}$ [@VerbuntHut; @Sigurdsson1992], reflecting the mean time since last bombardment. It is hard to know when the most recent bombardment episode was, and thus the constant factor out in front, but globular clusters can be ranked with respect to each other by a maximum-strain type figure of merit

$$\label{GCFOM}
h_{0} \propto \rho_{c}^{3/4} r_{c}/d,$$

where $\rho_{c}$ is the globular cluster core density, $r_{c}$ is the core radius, $d$ is the distance to the cluster, and thus $r_{c}/d$ is the angular radius of the core. We ranked the Harris catalog of globular clusters [@Harris1; @Harris2] by this figure of merit and looked at the top few choices, which were mainly nearby core-collapsed clusters. The closest is NGC 6397 at $\approx 2.2$ kpc, but it is at high declination. This lessens the Doppler modulation of any 