LIGO-Virgo-KAGRA Collaboration (LVK)

The LIGO-Virgo-KAGRA (LVK) collaboration runs the world’s network of gravitational-wave detectors: laser interferometers that sense ripples in spacetime from colliding black holes and neutron stars. The two LIGO detectors in Hanford, Washington, and Livingston, Louisiana, have 4-kilometer arms; Virgo, near Pisa, Italy, has 3-kilometer arms; and KAGRA in Japan is the first underground detector with cryogenic mirrors.

Flagship instruments

• LIGO Hanford and LIGO Livingston: twin 4-km interferometers, operated by Caltech and MIT (see Caltech Astronomy).
• Virgo: 3-km interferometer in Cascina, Italy.
• KAGRA: underground, cryogenic detector in Kamioka, Japan.

Recent results

LIGO made the first direct detection of gravitational waves on September 14, 2015, earning the 2017 Nobel Prize in Physics. In 2017 LIGO and Virgo caught a neutron-star merger, GW170817, also seen in gamma rays and light. The fourth observing run, O4, ran from May 24, 2023, to November 18, 2025, the longest yet. GWTC-4.0 brought the catalog to 218 candidates, and in May 2026 GWTC-5.0 raised the tally to 390 confirmed events, with O4 alone accounting for about 75% of all detections. GW250114, the clearest signal yet with a signal-to-noise ratio near 80, confirmed Hawking’s area theorem. In April 2026, LIGO-India broke ground in Maharashtra.

What to watch, 2026-2030

• From early to mid-November 2026: Intermediate Run IR1, six months with both LIGO detectors, Virgo with interruptions and KAGRA later.
• The fifth observing run, O5: plans and timeline still being refined.
• LIGO-India construction, which will add a fifth detector to the network.

Why scientists are converging here

Gravitational-wave astronomy has moved from single events to populations: how often black holes merge, how big they get, and whether some are products of earlier mergers. The 2026 catalog also gave an independent Hubble constant measurement about 25% more precise than earlier gravitational-wave results. “Gravitational wave” was the most-mentioned of the 40 terms in our Research Pulse count, in 1,065 astro-ph abstracts from April to September 2026. For the space-based future, see LISA.