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Observing Plans and Public Alerts

LIGO, Virgo and KAGRA Observing Run Plans

[16 July 2021 update; next update by 15 September 2021]
The LIGO-Virgo-KAGRA collaborations are making good progress in the updates of the Virgo (where installation of new hardware is complete), KAGRA, and LIGO detectors in preparation for O4. It is not yet possible to give a definitive start date for O4, as there are some continued supply chain delays and the impact of COVID continues. We can say at this time that the O4 observing run will not begin before August 2022. We expect to be able to give a better estimate for the start of O4 by 15 September 2021 and will issue an update then.


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 (Board Chair, KAGRA Scientific Congress); hisaaki.shinkai@oit.ac.jp

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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