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Observing Plans and Public Alerts

LIGO, Virgo and KAGRA Observing Run Plans

[15 March 2022 update; next update by 15 May 2022]

LIGO, Virgo, and KAGRA are closely coordinating to start the O4 Observing run together. We plan to start the O4 Observing run in mid-December 2022, though we are still working through delays resulting from the pandemic. An Engineering Run is planned to start in mid-November; low-latency alerts for candidate events identified during engineering time may be released, both to exercise the system and to preserve the scientific value. We are planning a webinar for late April to update the community about the status of work on the detectors and to discuss the remaining challenges in our current schedule.

LIGO projects a sensitivity goal of 160-190 Mpc for binary neutron stars. Virgo projects a target sensitivity of 80-115 Mpc. KAGRA should be running with greater than 1 Mpc sensitivity at the beginning of O4, and will work to improve the sensitivity toward the end of O4.

observing plan timeline

Timeline for the LIGO, Virgo, and KAGRA observing and upgrade intervals. As shown, the O4 run is expected to last a total of 13 months, with a break of one month during the run for minor commissioning and tuning of the detectors. This timeline reflects planning at the date indicated in the upper left. The plans will be influenced by technical challenges and opportunities, as well as observational science considerations. They will be updated to account for any significant changes.

If you have any questions, please contact the Spokespersons:
  • Patrick Brady (Spokesperson, LIGO Scientific Collaboration);
  • Giovanni Losurdo (Spokesperson, Virgo Collaboration);
  • Jun’ichi Yokoyama (Board Chair, KAGRA Scientific Congress);

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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