  Close hyperbolic encounters of black holes (BHs) generate certain Burst With
Memory (BWM) events in the frequency windows of the operational, planned, and
proposed gravitational wave (GW) observatories. We present detailed
explorations of the detectable parameter space of such events that are relevant
for the LIGO-Virgo-KAGRA and the International Pulsar Timing Array (IPTA)
consortia. The underlying temporally evolving GW polarization states are
adapted from Cho et al. [Phys. Rev. D 98, 024039 (2018)] and therefore
incorporate general relativistic effects up to the third post-Newtonian order.
Further, we provide a prescription to ensure the validity of our waveform
family while describing close encounters. Preliminary investigations reveal
that optimally placed BWM events should be visible to megaparsec distances for
the existing ground-based observatories. In contrast, maturing IPTA datasets
should be able to provide constraints on the occurrences of such hyperbolic
encounters of supermassive BHs to gigaparsec distances.
