LIGO, VIRGO AND KAGRA OBSERVING RUN PLANS

(15 July 2025 update; next update 15 August 2025 or sooner)

The LIGO Hanford (LHO), LIGO Livingston (LLO), Virgo, and KAGRA detectors resumed the fourth observing run (O4) at 15:00 UTC on Wednesday, 11 June 2025. O4 will last until 16:00 UTC on Tuesday, 18 November 2025, with no further planned breaks in observing.

LIGO, Virgo, and KAGRA (LVK) continually assess their planned commissioning and upgrade activities. New threats to planned funding levels are creating greater uncertainty in our observing schedules, both for the end of O4 and the beginning of O5. As the funding situation becomes clearer, the LVK will be assessing the best way forward to maximize the scientific output of the global network in the longer term. Updates to the observing schedule will be provided as soon as such decisions are made.

For more information, see:

OpenMMA wiki - https://github.com/scimma/openMMA/wiki

IGWN public alert user guide - https://emfollow.docs.ligo.org/userguide

Timeline

The gravitational-wave observing schedule is divided into Observing Runs, down time for construction and commissioning, and transitional Engineering Runs between commissioning and observing runs. The current best understanding of the long-term observing schedule is shown below (or https://dcc.ligo.org/LIGO-G2002127/public). Since BNS (Binary Neutron Star) mergers are a well-studied class of gravitational-wave signals, this figure gives the BNS range for for a single-detector SNR threshold of 8 in each observing run.

Long-term observing schedule

Plans and timeline for the fifth observing run (O5) are being reassessed. Further information will be provided as soon as it becomes available.

Live Status

A public web page that report live status of the LIGO/Virgo detectors and alert infrastructure is at

– Page Design adapted from the LIGO/Virgo/KAGRA Public Alerts User Guide –