On June 15, 2024, two black holes—one weighing 26 times the mass of our sun, the other 30 times—collided more than 3 billion light-years away, and scientists on Earth captured the moment with unprecedented clarity. That single gravitational wave signal, named GW240615, achieved the most precise sky localization in the history of gravitational-wave astronomy, pinpointing the cosmic explosion to just 6 square degrees of the celestial sphere.
This breakthrough is part of something far larger: a watershed moment for an entire field of science. Researchers from the University of Glasgow's Institute for Gravitational Research and the international LVK collaboration—comprising the LIGO detectors in the United States, Virgo in Italy, and KAGRA in Japan—have published the Gravitational Wave Transient Catalogue-5.0, or GWTC-5, documenting 161 new gravitational wave signals detected between April 2024 and January 2025. That brings the total number of confirmed detections to 390 since the first direct observation in September 2015, a milestone that marks gravitational astronomy coming of age.
The scale of what this represents is staggering. A decade ago, the first gravitational wave detection was headline news around the world. Now the collaboration is picking up between three and four signals each week, each one revealing the violent collision of distant black holes. "Just ten years ago, we made the first detection of gravitational waves from one of these events, and it's a real testament to the work of hundreds of scientists around the world that we're now detecting and analyzing hundreds of them," said Dr. Daniel Williams, a research fellow at the Institute and co-chair of the Compact Binary Science Working Group.
The science unlocked by this torrent of data is as profound as the numbers are impressive. The latest catalog contains the first measurement of three vibrational modes of a black hole—essentially reading the "ringing" of spacetime itself after two black holes merge. It offers evidence for the existence of second-generation black holes, objects born from the collision of two earlier black holes rather than from stellar collapse. And it delivers the clearest gravitational wave signal ever recorded, allowing physicists to extract details about cosmic objects with precision that seemed impossible just years ago.
The University of Glasgow has been central to making this explosion of discovery possible. Since the 1970s, its astrophysicists have led development of the delicate mirror suspensions at the heart of LIGO's detectors—the exquisitely sensitive instruments that can measure shifts billions of times smaller than an atomic nucleus. As the detectors have grown more sensitive through successive upgrades, more events have revealed themselves. The collaborative cycle of observation, analysis, detector improvement, and re-analysis means the gravitational wave catalog is now updated and shared with the scientific community roughly every six months.
Dr. Williams captured the deeper significance: "At Glasgow we've been at the forefront of developing new technology to make the detectors more sensitive, allowing us to see more of these signals, more clearly, and from collisions much further away than we could a decade ago." With more sensitive observing runs coming, and detections expected to accelerate, gravitational wave astronomy is no longer a novelty—it is opening a permanent new window onto the universe's most violent and mysterious events.