(15 November 2023 update; next update 15 December 2023 or sooner)

We started the O4 Observing run on 24 May 2023. The observing run will last 20 calendar months including up to 2 months of commissioning breaks for maintenance.

The LIGO Hanford (LHO) and Livingston (LLO) detectors continue to observe with good availability. In the past month, LHO and LLO have operated at binary-neutron-star (BNS) ranges between 155 and 170 Mpc. The duty cycle for LHO has been 70%, and for LLO 75%. We continue to seek ways to improve the sensitivity and duty cycle as the run proceeds.

The LIGO Commissioning break will begin on 16 January 2024, with a planned duration of two months. The main activities for this period have been determined; one of the corrective actions is expected to mitigate an identified variable noise coupling, but no large increases in sensitivity are expected.

The recent commissioning activities have allowed the Virgo detector to achieve a BNS range up to 35 Mpc. The plan for the forthcoming months aims at mitigating known noise sources to further enhance sensitivity up to a range of 40-45 Mpc, and at addressing excess broadband noise in the most sensitive part of the frequency range (80-200 Hz) to reduce, at least in part, the residual gap with design sensitivity. The Virgo Collaboration has set the ultimate date for Virgo to join O4 in March 2024, independently from the sensitivity achieved at that time. The exact date will be finalized in agreement with LVK partners and will be announced as soon as possible. At the moment, Virgo is reconsidering its plans for O5 and both the date on which we will be able to enter O5 and the target sensitivity are currently unclear. We expect to be able to define our plans for O5 around mid-2024.

KAGRA restarted commissioning on 3 July 2023, and will rejoin the observing run in spring 2024, with a BNS range of around 10 Mpc.

Please check the OpenLVKEM pages for the timing and coordinates for telemeetings. The schedule of calls is posted at the OpenLVKEM wiki (see below), along with Agenda and pointers to materials.

Reference Material:


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. 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

The O5 start dates, duration, and sensitivities are current best guesses, and will likely be adjusted as we approach that run. For Virgo the graphics represents the initial plan established in 2019. This plan is being currently reconsidered (see text).

Live Status

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