An even loftier goal is pinning down the gravitational wave background—you can think of it as the entire ocean of gravitational waves, dynamically criss-crossing as they are produced by black hole and neutron star collisions throughout the cosmos.

Source: https://gizmodo.com/brightest-gamma-ray-burst-ever-the-boat-1850273973

Currently, the biggest black hole merger ever detected by Earth's gravitational wave observatories resulted in a with a mass of 142 solar masses (or 142 times our Sun's mass).

Source: https://www.salon.com/2023/01/13/two-huge-black-holes-are-on-the-verge-of-collision-when-they-do-the-explosion-will-be-incalculable/