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    LIGO, Virgo and KAGRA gravitational-wave detectors

    Also known as LVK, LIGO, Virgo, KAGRA, LIGO-Virgo-KAGRA Collaboration

    LIGO, Virgo and KAGRA are laser interferometers in the US, Italy and Japan that together detect gravitational waves, ripples in spacetime from merging black holes and neutron stars.[1][2] Their fourth run, which ended in November 2025, recorded about 250 candidates, bringing the total to roughly 350; a new six-month run is planned from November 2026.[3][4][5]

    Editor reviewedUpdated Particle physics and cosmologyPhysicsScience
    Key facts

    What it is

    The network has four large laser interferometers: the two LIGO detectors at Hanford and Livingston in the United States, Virgo near Pisa in Italy, and KAGRA at Kamioka in Japan.[1] Each one detects the tiny stretching of space caused by gravitational waves passing through. The first detection, in 2015, came from two black holes of 30 to 40 solar masses merging about 1.3 billion light-years away.[2]

    The fourth observing run

    The fourth run (O4) lasted from 24 May 2023 to 18 November 2025 and recorded roughly 250 candidate signals in real time.[3] That is more than two-thirds of the roughly 350 gravitational-wave signals detected to date.[4] The GWTC-4.0 catalogue, released in August 2025, added 128 candidates from the first part of O4, bringing the catalogue total to 218.[6] As of November 2025 the remaining parts of O4 were still being analysed.[7]

    The next catalogue, GWTC-5.0, came out on 26 May 2026. It added 161 events from the O4b period (10 April 2024 to 28 January 2025), bringing the total confirmed since 2015 to 390. O4 alone accounts for about 75% of all gravitational-wave events ever detected.[8] Because GWTC-5.0 stops at January 2025 and O4 ran until November 2025, events from the last part of the run are not yet in a catalogue.[8][3]

    Notable signals

    • GW250114, detected on 14 January 2025, is the clearest signal yet. It gave the best observational evidence to date for Hawking’s black hole area theorem, which says the total horizon area cannot decrease.[9]
    • GW231123 is the most massive merger observed, producing a final black hole more than 225 times the mass of the Sun.[10]
    • GW240615, seen by both LIGO detectors and Virgo on 15 June 2024, was pinned down to about 6 square degrees of sky, the most precise localisation of any gravitational-wave source so far.[11] Collaboration scientists credit the third detector: with Virgo’s independent measurements, the network can triangulate sources to within a few square degrees.[12] Precise localisation lets telescopes such as the Rubin Observatory search for light from the same event, the approach called multi-messenger astronomy.[13]

    What comes next

    As of September 2026 the collaborations plan a six-month observing run, IR1, starting in early to mid-November 2026. Plans and timing for the longer fifth run (O5) are still under discussion.[5] Both LIGO detectors are to observe in IR1. Virgo will join but may pause for maintenance, and KAGRA will join later in the run.[14]

    A fifth detector is under construction. LIGO-India broke ground on 23 April 2026 at Aundha in Maharashtra. Funded by the Indian government, it will copy the design of the two US LIGO detectors, with two 4-km arms, and aims to start observing in 2030.[15] In space, ESA adopted the LISA mission on 25 January 2024. Its three spacecraft will form a triangle with 2.5-million-km sides and are planned to launch in 2035.[16]

    Questions readers ask

    What was special about GW250114?

    It is the clearest gravitational-wave signal yet. It gave the best observational evidence so far for Hawking's theorem that black hole horizon area cannot shrink.[9]

    How many gravitational waves have been detected?

    About 350 signals by the end of the fourth observing run in November 2025, more than two-thirds of them during that run.[4]

    When do the detectors observe next?

    The collaborations plan a six-month run called IR1 from early to mid-November 2026. Plans for the longer fifth run (O5) are still under discussion.[5]

    Will there be detectors in space?

    Yes. ESA adopted the LISA mission in 2024, with three spacecraft planned to launch in 2035.[16]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      The LIGO-Virgo-KAGRA network consists of the two LIGO detectors at Hanford and Livingston in the US, Virgo near Pisa in Italy, and KAGRA at Kamioka in Japan. confirmedas of 2025-11-18

    2. [2]

      The first gravitational-wave detection, in 2015, came from merging black holes of 30 to 40 solar masses about 1.3 billion light-years away. confirmedas of 2025-09-10

    3. [3]

      The fourth LIGO-Virgo-KAGRA observing run ran from 24 May 2023 to 18 November 2025 and recorded roughly 250 candidate signals in real time. confirmedas of 2025-11-19

    4. [4]

      About 350 gravitational-wave signals had been detected by the end of O4, more than two-thirds of them during O4. confirmedas of 2025-11-18

    5. [5]

      As of September 2026 the collaborations plan a six-month observing run, IR1, beginning in early to mid-November 2026, while plans and timing for the fifth observing run (O5) are still under discussion. confirmedas of 2026-09-03

    6. [6]

      The GWTC-4.0 catalogue, released in August 2025, added 128 new candidates from the first part of O4 (May 2023 to January 2024), bringing the catalogue total to 218. confirmedas of 2025-08-26

    7. [7]

      As of November 2025, data from the remaining two segments of O4 were still under detailed examination, with further results expected in the following months. confirmedas of 2025-11-19

    8. [8]

      The GWTC-5.0 catalogue, released on 26 May 2026, added 161 gravitational-wave events from the O4b period (10 April 2024 to 28 January 2025), bringing the total confirmed since 2015 to 390, with O4 alone accounting for about 75% of all events. confirmedas of 2026-05-26

    9. [9]

      GW250114, detected on 14 January 2025, is the clearest gravitational-wave signal yet and gave the best observational evidence to date for Hawking's black hole area theorem; results appeared in Physical Review Letters. confirmedas of 2025-09-10

    10. [10]

      GW231123 is the most massive black hole merger observed, producing a final black hole more than 225 times the mass of the Sun. confirmedas of 2025-11-18

    11. [11]

      GW240615, detected by the two LIGO detectors and Virgo on 15 June 2024, was localised to about 6 square degrees of sky, the most precise localisation of any gravitational-wave event so far. confirmedas of 2026-05-26

    12. [12]

      LIGO-Virgo-KAGRA scientists say adding Virgo's independent measurements lets the network triangulate sources to within a few square degrees, sharp enough to guide multi-messenger follow-up. confirmedas of 2026-05-26

    13. [13]

      Rubin's rapid colour observations of transients, such as stellar explosions and collisions between compact objects, are intended to guide follow-up for multi-messenger astronomy, which combines light with signals such as gravitational waves and cosmic rays. confirmedas of 2026-06-30

    14. [14]

      Both LIGO detectors are planned to observe in IR1, with Virgo joining subject to maintenance interruptions and KAGRA joining later in the run. confirmedas of 2026-09-03

    15. [15]

      LIGO-India, funded by the Indian government, broke ground on 23 April 2026 at Aundha in Maharashtra; it will be an Advanced LIGO interferometer with two 4-km arms identical in design to the US detectors, with first observations targeted for 2030. confirmedas of 2026-04-23

    16. [16]

      ESA adopted the LISA space gravitational-wave observatory on 25 January 2024; its three spacecraft, forming a triangle with 2.5-million-km sides, are planned to launch in 2035. confirmedas of 2024-01-25

    Revision history (2)
    1. Page created.
    2. Added GWTC-5.0 (May 2026, 390 events), GW240615, IR1 detector line-up and the LIGO-India groundbreaking; linked Rubin for multi-messenger follow-up.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "LIGO, Virgo and KAGRA gravitational-wave detectors." ContentLora, updated Oct 10, 2026. https://contentlora.com/wiki/ligo-virgo-kagra

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