LIGO, VIRGO AND KAGRA OBSERVING RUN PLANS

(18 November 2025 update; next update 15 February 2026 or sooner)

The fourth observing run (O4) concluded, as planned, on 18 November 2025. LIGO, Virgo, and KAGRA interferometers are starting a period of upgrades and commissioning. Engineering class alerts may be sent in the case of extraordinary events that may be found during the initial upgrade phase, through December 9th, 2025. After recent assessments of upgrade phasing and discussions with funding agencies, we currently envision a six-month observing run to begin in the late summer/early fall of 2026, with detectors participating as available. We will update this page as the plans become firmer.

For more information on LVK Observing, 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.

Detector Status

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