The LIGO, Virgo and KAGRA collaborations have declared that, mainly because of COVID-related issues, the fourth observation period, known as 'O4', will not begin before June, 2022. The three scientific collaborations foresee further potential refinements in the coming months, as the impact of the pandemic on the scheduled detector upgrades is more fully understood.

Hereafter, follows the official statement of the LIGO–Virgo–KAGRA collaboration and the observatory directors. "The LIGO–Virgo–KAGRA collaborations have reviewed the readiness status of the detectors improvements and A+/AdV+ modifications in preparation for the fourth observing period (O4). As of November 2020, the O4 observing run is projected not to begin before June 2022, due to both key procurement delays and COVID-related delays. A number of significant modifications to detector systems during the next six months will refine the understanding of COVID impacts on the schedule. A revised projection of the O4 start date will be given in spring 2021, based on lessons learned."

Image: The roof cover on the north arm of Virgo was elevated during the summer of 2020, to allow for the installation of new suspensions and small clean rooms, required for an additional 300-metre-long optical-cavity. This installation is part of the Advanced Virgo+ upgrade, which aims to improve the sensitivity of the detector before the next data-taking period (O4).

Image credit: EGO/Fabozzi