List of gravitational wave observations

Probable detections that are not confidently identified as gravitational wave events are designated LVT ("LIGO-Virgo trigger").

It was published in 2020 that a gamma-ray burst was detected (GRB 190425) ~0.5 seconds after the LIGO trigger, lasting 6 seconds and bearing similarities to GRB170817 (such as weakness [most power in sub-100 keV, or soft X-rays) bands], elevated energetic photon background levels [signal exceeding background by less than a factor of 2], and similar differences from other transients classified as short GRBs).

Confidence was established for interpretation of a set of peaks through a control interval of only 2 days prior to the LIGO-Livingston trigger in INTEGRAL Electronic anticoincidence, could not be corroborated by other instruments and wasn't initially noted as a significant event.

[36] 2023-05-29 18:15:00 There is possible detection of nanohertz waves by observation of the timing of pulsars, but they have not been confirmed at the 5 sigma level of confidence, as of 2023[update].

False alarm rates are mixed, with more than half of events assigned false alarm rates greater than 1 per 20 years, contingent on presence of glitches around signal, foreground electromagnetic instability, seismic activity, and operational status of any one of the three LIGO-Virgo instruments.

[70] However, KAGRA does not report their signals in real-time on GraceDB as LIGO and Virgo do, so the results of their observation run will likely not be published until the end of O3.

[83] On March 7, 2023, a gamma-ray burst compatible with a neutron star merger was detected by the Fermi telescope and named GRB 230307A.

However, the Mw7.5 2024 Noto earthquake occurred on 1 January 2024 only 103 kilometres (64 mi) from KAGRA, damaging the detector's sensitive instruments and delaying its development by at least several months.

On 18 May 2023, near the end of the engineering run and shortly before O4 proper, the first candidate gravitational wave event was detected.

In October, LIGO announced a planned pause between January and March 2024, for a mid-run commissioning break intended to reduce noise and improve the uptime of the detectors.