Identification and follow up of electromagnetic counterparts of gravitational wave candidate events

The LIGO Scientific Collaboration (LSC) and the Virgo Collaboration have started taking data in 2015, and we expect the sensitivity of the network to improve over time. Gravitational-wave transient candidates will be identified promptly upon acquisition of the data; we aim for distributing information with an initial latency of a few tens of minutes initially, possibly improving later. The LSC and the Virgo Collaboration (LVC) wish to enable multi-messenger observations of astrophysical events by GW detectors along with a wide range of telescopes and instruments of mainstream astronomy.

In 2012, the LVC approved a statement (LSC, Virgo) that broadly outlines LVC policy on releasing GW triggers (partially-validated event candidates). Initially, triggers will be shared promptly only with astronomy partners who have signed a Memorandum of Understanding (MoU) with LVC involving an agreement on deliverables, publication policies, confidentiality, and reporting. After four GW events have been published, further event candidates with high confidence will be shared immediately with the entire astronomy community (and the public), while lower-significance candidates will continue to be shared promptly only with partners who have signed an MoU.

From June to October 2013, we organized rounds of consultations with groups of astronomers that have expressed interest in the GW-EM follow-up program. Thanks to these consultations, we defined the framework and guiding rules for this program that are detailed here and collected into a standard MoU template.

Open calls for proposals to sign the standard MoU with LVC were issued in December 2013, December 2014, and December 2015. Over 70 teams of professional astronomers and agencies have signed an MoU with LVC so far.

Please direct inquiries to

We welcome comments on this process sent to the LSC Spokesperson, and to the Virgo Spokesperson.

Useful links and documents

Current Open Call for Partnership for the EM Identification and Follow-up of GW Candidate Events
Current Template and Application Form for the Agreement Regarding Follow-up Observations of Gravitational Wave Event Candidates
Current Partial list of participating observers
August/September 2013 Discussion Meeting about agreements for LIGO-Virgo Event Follow-up Program in Amsterdam and Chicago
June 2013 Open Call for Letters of Interest
April 2013 Prospects for Localization of Gravitational Wave Transients by the Advanced LIGO and Advanced Virgo Observatories
January 2013 LIGO Data Management Plan
May 2012 LSC and VIRGO policy on releasing gravitational wave triggers to the public in the advanced detector era

An artist's rendition of two neutron stars.

Devour thy Neighbor: An artist's illustration of two neutron stars close to merger look misshaped, becoming more oblong the closer they get to one another. A black hole is then formed and gamma rays shoot out as a GRB. (Credit: NASA/Swift)

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