December 9, 2020
The LIGO-Virgo-KAGRA collaborations have reviewed the readiness status of the detectors improvements and A+/AdV+ modifications in preparation for 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.
Patrick, Giovanni, Hisaaki, Dave, Albert, Stavros, Takaaki, Masatake