This award supports research in relativity and relativistic astrophysics, addressing the priority areas of NSF's "Windows on the Universe" Big Idea. Gravitational waves and black holes are among the most dramatic predictions of Einstein's theory of General Relativity. The NSF's Laser Interferometer Gravitational-wave Observatory (LIGO) has transformed our understanding of the universe by detecting gravitational waves from colliding black holes and neutron stars. As part of the International Gravitational-Wave Observatory Network (IGWN), LIGO provides an entirely new way to study the most extreme phenomena in the universe. The first direct observation of gravitational waves by LIGO in 2015 positioned the United States as a world leader in gravitational-wave science. Detecting weak gravitational-wave signals requires substantial computational infrastructure that spans astrophysical data analysis, detector and analysis middleware, software sustainability, and computational hardware support. This project addresses a critical challenge: sustaining and enhancing the computational infrastructure required to transform detector data into groundbreaking scientific discoveries. Gravitational-wave astronomy relies on the timely analysis of continuous data streams from the global network of detectors and the coordinated efforts of approximately 3,000 scientists. The computational needs are served by the IGWN Computing Grid, a distributed facility that provides the backbone enabling rap