Gamma-ray bursts (GRBs) are high-energy astrophysical transients originating throughout the universe that are observed more than once per day on average. The prompt gamma-ray emission is thought to emanate from highly relativistic jets powered by matter interacting with a compact central object such as an accreting black hole (BH) or a magnetar (Woosley 1993). Broadly speaking, GRBs are divided into two subpopulations based on duration and spectral hardness (Kouveliotou et al. 1993). Long-soft bursts generally have durations 2s. The favored model is the core-collapse supernova (SN) of a rapidly rotating massive star (Woosley & Bloom 2006; Mösta et al. 2015). This connection was observationally supported by the presence of SN 1998bw within the error box of the long GRB 980425 (Galama et al. 1998) and the later strong association of SN 2003dh with GRB 030329 (Hjorth et al. 2003; Stanek et al. 2003). The core-collapse process will produce some gravitational radiation (Fryer & New 2011). Rotational instabilities may give rise to much more significant gravitational-wave (GW) emission, however, and could be observable from beyond the Milky Way (Davies et al. 2002; Fryer et al. 2002; Kobayashi & Meszaros 2003; Shibata et al. 2003; Piro & Pfahl 2007; Corsi & Meszaros 2009; Romero et al. 2010; Gossan et al. 2016).

Neutron star (NS) binaries have long been proposed as the progenitors of short-hard GRBs (Blinnikov et al. 1984; Paczynski 1986; Eichler et al. 1989; Narayan et al. 1992). The detection of the GW transient GW170817, an NS binary merger (Abbott et al. 2017a, 2017e, 2019b), in coincidence with the