Multi-messenger observations of a binary neutron star merger

Research output: Contribution to journalReview articlepeer-review


  • LIGO Scientific Collaboration
  • Virgo Collaboration
  • Fermi GBM
  • Icecube Collaboration
  • AstroSat Cadmium Zinc Telluride Imager Team
  • IPN Collaboration
  • The Insight-Hxmt Collaboration
  • ANTARES Collaboration
  • The Swift Collaboration
  • AGILE Team
  • The 1M2H Team
  • The Dark Energy Camera GW-EM Collaboration and the DES Collaboration
  • The DLT40 Collaboration
  • GRAWITA: GRAvitational Wave Inaf TeAm
  • ATCA: Australia Telescope Compact Array
  • ASKAP: Australian SKA Pathfinder
  • Las Cumbres Observatory Group
  • OzGrav, DWF (Deeper Wider Faster program) AST3 and CAASTRO Collaborations
  • The VINROUGE Collaboration
  • MASTER Collaboration
  • J-GEM
  • GROWTH JAGWAR Caltech-NRAO TTU-NRAO and NuSTAR Collaborations
  • Pan-STARRS
  • TZAC Consortium
  • The MAXI Team
  • KU Collaboration
  • Nordic Optical Telescope
  • Texas Tech University
  • SALT Group
  • TOROS: Transient Robotic Observatory of the South Collaboration
  • The BOOTES Collaboration
  • MWA: Murchison Widefield Array
  • IKI-GW Follow-up Collaboration
  • The CALET Collaboration
  • H.E.S.S. Collaboration
  • LOFAR Collaboration
  • LWA: Long Wavelength Array
  • HAWC Collaboration
  • The Pierre Auger Collaboration
  • ALMA Collaboration
  • Euro VLBI Team
  • Pi of the Sky Collaboration
  • The Chandra Team at McGill University
  • DFN: Desert Fireball Network
  • ATLAS Collaboration
  • High Time Resolution Universe Survey
  • Matt Nicholl

External organisations

  • California Institute of Technology
  • Louisiana State University
  • Universita degli Studi di Salerno
  • Complesso Universitario di Monte S.Angelo
  • University of Florida
  • Monash University
  • LIGO Livingston Observatory
  • LAPP, Université de Savoie, CNRS/IN2P3
  • University of Sannio at Benevento
  • Max Planck Institute for Gravitational Physics (Albert Einstein Institute) Am Mühlenberg 1, D-14476 Potsdam, Germany
  • University of Mississippi
  • University of Illinois at Urbana-Champaign
  • University of Cambridge
  • Institution Nikhef National Institute for Subatomic Physics
  • Massachusetts Institute of Technology
  • Instituto Nacional de Pesquisas Espaciais
  • Facebook
  • Laboratori Nazionali del Gran Sasso
  • Inter-University Centre for Astronomy and Astrophysics India
  • Tata Institute of Fundamental Research
  • University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA
  • Institut für Gravitationsphysik (Albert-Einstein-Institut)
  • Università di Pisa
  • Sezione INFN di Pisa
  • The Australian National University
  • Domaine Scientifique de la Doua
  • University of the West of Scotland
  • IN2P3


On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 M. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.


Original languageEnglish
Article numberL12
Number of pages59
JournalAstrophysical Journal Letters
Issue number2
Publication statusPublished - 16 Oct 2017


  • Gravitational waves, Stars: neutron