The international network of deep space gravitational wave detectors operated by the LIGO–Virgo–KAGRA (LVK) Collaboration has announced the online release of an updated catalog of all gravitational wave events observed to date, named the Gravitational Wave Transient Catalog-5.0 (GWTC-5.0).
Gravitational waves are “ripples” in space-time that result from cataclysmic events in deep space. This updated catalog includes the most recent gravitational wave events that occurred between April 10, 2024 and January 28, 2025, during a portion of the network’s fourth observing run, known as O4b. During this period, 161 new gravitational wave events were detected, bringing the total number of confirmed events observed by the network since the first detection in 2015 to 390.
“The gravitational-wave events accumulated in our catalog have ushered us into a new era of statistical astronomy—where this growing collection of detected signals enables population studies and tests of general relativity with unprecedented precision,” said Leo Tsukada, a collaborating scientist and postdoctoral research fellow with the Nevada Center for Astrophysics at UNLV.
The data assembled for the most recent catalog were collected by the twin detectors of the US National Science Foundation Laser Interferometer Gravitational-wave Observatory (NSF LIGO) and the Virgo detector operated by the European Gravitational Observatory (EGO), with analysis carried out in collaboration with the KAGRA Collaboration, an international consortium centered on the KAmioka GRAvitational wave detector in Japan.
“Crucially, the inclusion of Virgo in our detector network has been transformative as its independent measurements allow us to triangulate sources across the sky with a few square degree accuracy, turning fuzzy patches of uncertainty into sharp localizations,” said Tsukada. “This sets a strong foundation for the next-generation observing era with an expanded global detector network.”
A Rise in Gravitational Wave Detections
With the release of the updated catalog, the fourth observing run alone now accounts for roughly 75% of all gravitational wave events detected since the first observation in 2015. This impressive result demonstrates how crucial detector upgrades are for increasing sensitivity, leading to an extraordinary growth in the number of detected events with each successive observing run.
The international LVK Collaboration alternates periods of data collection (observing runs) with phases devoted to detector upgrades and commissioning. That’s why the gravitational wave event catalog—including validated data and the physical parameters of the sources—is updated and shared with the wider scientific community periodically.
“We are now seeing the impacts of gravitational-wave astronomy across the scientific community,” said Jonah Kanner, a senior scientist for the LIGO Laboratory at Caltech. “Our data releases are cited in over 200 scientific papers each year, and thousands of young and aspiring scientists have enrolled in our annual Open Data Workshops. This data set will be a treasure trove for researchers learning about cosmology, stellar evolution, theories of gravity, and many other open questions in physics and astronomy.”
The new catalog also includes several detections that set new records in gravitational-wave astronomy observations, including the best sky localization ever achieved for a gravitational wave source, the clearest gravitational wave signal ever recorded, and evidence for the existence of second-generation black holes.
The Best Sky Localization Ever Achieved
A signal detected by the two LIGO detectors in the United States and Virgo in Europe on June 15, 2024 set the record for the most precise sky localization among all gravitational wave events observed to date. The source was identified within an area of just 6 square degrees, a relatively small portion of the celestial sphere. This exceptional performance was achieved thanks to the triangulation using data from all three detectors active at the time, including Virgo, which rejoined the observing campaign in April 2024 at the beginning of O4b, contributing significantly to the network’s source-localization capabilities.
Localization of sources in the sky enables astronomers to search for other astronomical signals that may be associated with the gravitational wave event. The gravitational wave event observed with this record localization was the merger of two black holes, with masses of about 26 and 30 solar masses, which violently collided more than 3 billion light-years from Earth.
Clearest Gravitational Wave Signal Ever Recorded
Detecting gravitational waves does not simply mean capturing a signal, but extracting it from the noise that disturbs the detectors. This requires intense noise-mitigation efforts and highly sophisticated data analyses, which is why the “strength” or “clarity” of a signal is expressed through the signal-to-noise ratio.
The new catalog published includes the “clearest” gravitational wave signal ever detected, with a signal-to-noise ratio of 76.9. This previously announced signal, GW250114, reached Earth on January 14, 2025 and was generated by the merger of two black holes with nearly identical masses (32 and 34 times the mass of the Sun, respectively), occurring more than one billion light-years from Earth. Its “clarity” has led to some exceptional scientific results, which have already been published and announced by the LVK collaboration in recent months, including the most accurate test of general relativity ever performed and confirmation of Stephen Hawking’s black hole area theorem.
Second-Generation Black Holes
Another outstanding result that has been reported on and is included in the new catalog concerns two very special events: GW241011 and GW241110. These signals, detected just one month apart in October and November 2024, were generated by two black hole mergers located approximately 700 million and 2.4 billion light-years from Earth. Characteristics of these mergers, in particular the spin of the black holes, indicate the objects involved could be ‘second-generation’ black holes, meaning black holes that are themselves the result of previous coalescences. These objects likely formed in very dense and crowded cosmic environments, such as stellar clusters, where black holes are more likely to collide and merge repeatedly.
“Each new detection provides important insights about the universe, reminding us that each observed merger is both an astrophysical discovery but also an invaluable laboratory for probing the fundamental laws of physics,” says Carl-Johan Haster, assistant professor of astrophysics at UNLV. “Binaries like these had been predicted given earlier observations, but this is the first direct evidence for their existence.”
The growing number of observed events has also enabled researchers to study and more clearly identify the properties of different populations of black holes. In particular, they now find that these second-generation black holes may form a distinct sub-group that shares certain characteristic properties.
Collaboration Sets Focus on Future Discoveries
Corresponding scientific papers from the the Gravitational Wave Transient Catalog-5.0 (GWTC-5.0) are being submitted to Astrophysical Journal and Astrophysical Journal Letters.
Scientists say that there is still more data to analyze from the fourth observing run, with the final portion set to be publicly released in December. The LVK Collaboration celebrates this significant update to the catalog of observed gravitational wave events, the global team that made it possible, and the discoveries still to come.
“We have an outstanding team of scientists, engineers and supporting staff who build, operate and improve these amazing detectors, and who analyze the data with great care to answer scientific questions,” said Peter Shawhan, deputy spokesperson of the LIGO Scientific Collaboration and professor of physics at the University of Maryland. “Some keep the observatories at peak performance while many others work and study at universities, colleges and research institutions near and far away. It's the global, interconnected team of creative, dedicated people which makes the most ambitious science possible.”
