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Observing Plans and Public Alerts

LIGO, Virgo and KAGRA Observing Run Plans

[10 December 2020 update; next update in Spring 2021]
The LIGO-Virgo-KAGRA collaborations have reviewed the readiness status of the detector 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.


If you have any questions, please contact the Spokespersons:
  • Patrick Brady (Spokesperson, LIGO Scientific Collaboration); lsc-spokesperson@ligo.org
  • Giovanni Losurdo (Spokesperson, Virgo Collaboration); virgo-spokesperson@ego-gw.it
  • Hisaaki Shinkai (Spokesperson, KAGRA Collaboration); hisaaki.shinkai@oit.ac.jp

Additional information on the status of LIGO Laboratory operations in reference to COVID-19 can be found here.

O3 observing run timeline

  • Start date: 1 April 2019
  • Commissioning break: 1-31 October 2019
  • Observing ended: 27 March 2020

Public Alerts in O3

  • Public Alerts for O3 ended on 27 March 2020.
  • Alerts are issued through the GCN/TAN system.
  • For more information and usage examples, see the LIGO/Virgo Public Alerts User Guide.
  • The official candidate event database is GraceDB.
  • For the general public, a more accessible view is maintained on the Chirp website; mobile apps are also available there.

triangulation of GW170817

GW170817 Localization and Triangulation Annuli. We can pinpoint sources like GW170817 much more accurately now that we can triangulate the signal between Hanford, Livingston, and Virgo. The rapid Hanford-Livingston localization is shown in blue, and the final Hanford-Livingston-Virgo localization is in green. The gray rings are one-sigma triangulation constraints from the three detector pairs. [Credit: LIGO/Virgo/NASA/Leo Singer (Milky Way image: Axel Mellinger)]

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