LIGO, VIRGO AND KAGRA OBSERVING RUN PLANS

(13 February 2026 update; next update 15 April 2026 or sooner)

The fourth observing run (O4) concluded on 18 November 2025. LIGO, Virgo, and KAGRA interferometers are now in a period of upgrades and commissioning. Short windows of low noise data collection during the period of upgrades are possible and, if quality data indicate an exceptional gravitational-wave event, a public alert will be sent.

We are currently planning a six-month observing run, designated as IR1, beginning sometime between mid-September and early-October of 2026. Both LIGO detectors will be observing in IR1, and Virgo and KAGRA will join as they are available. We will update this page as the plans become firmer.

LIGO, Virgo and KAGRA are still working toward the sensitivity goals for a future long observing run (O5 in the figure), but the timing of that run following the upgrades is less certain and will be refined in future updates.

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

Both LIGO detectors will be observing in IR1, and Virgo and KAGRA will join as they are available. 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 –