Article open access publication

Swift and NuSTAR observations of GW170817: Detection of a blue kilonova

Science, American Association for the Advancement of Science (AAAS), ISSN 0036-8075

Volume 358, 6370, 2017

DOI:10.1126/science.aap9580, Dimensions: pub.1092248394, PMID: 29038371,



  1. (1) University of Leicester, grid.9918.9
  2. (2) University of Maryland, College Park, grid.164295.d
  3. (3) Astrophysics Science Division, grid.468494.3
  4. (4) Pennsylvania State University, grid.29857.31
  5. (5) University College London, grid.83440.3b
  6. (6) Los Alamos National Laboratory, grid.148313.c
  7. (7) California Institute of Technology, grid.20861.3d
  8. (8) Tel Aviv University, grid.12136.37
  9. (9) Simons Foundation, grid.430264.7
  10. (10) Department of Physics, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
  11. (11) Goddard Space Flight Center, grid.133275.1
  12. (12) Istituto Nazionale di Astrofisica (INAF)–Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate, Italy
  13. (13) University of Warwick, grid.7372.1
  14. (14) INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica Palermo, via Ugo La Malfa 153, I-90146, Palermo, Italy
  15. (15) Space Science Data Center–Agenzia Spaziale Italiana (ASI), I-00133 Roma, Italy
  16. (16) INAF–Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone, Italy
  17. (17) Istanbul University, grid.9601.e
  18. (18) Southern Utah University, grid.263886.1
  19. (19) Clemson University, grid.26090.3d
  20. (20) National Science Foundation, grid.431093.c
  21. (21) Universities Space Research Association, grid.410493.b
  22. (22) University of Copenhagen, grid.5254.6, KU
  23. (23) Stockholm University, grid.10548.38
  24. (24) Aoyama Gakuin University, grid.252311.6


With the first direct detection of merging black holes in 2015, the era of gravitational wave (GW) astrophysics began. A complete picture of compact object mergers, however, requires the detection of an electromagnetic (EM) counterpart. We report ultraviolet (UV) and x-ray observations by Swift and the Nuclear Spectroscopic Telescope Array of the EM counterpart of the binary neutron star merger GW170817. The bright, rapidly fading UV emission indicates a high mass (≈0.03 solar masses) wind-driven outflow with moderate electron fraction (Ye ≈ 0.27). Combined with the x-ray limits, we favor an observer viewing angle of ≈30° away from the orbital rotation axis, which avoids both obscuration from the heaviest elements in the orbital plane and a direct view of any ultrarelativistic, highly collimated ejecta (a γ-ray burst afterglow).


Research Categories

Main Subject Area

Fields of Research

Links & Metrics

NORA University Profiles

University of Copenhagen

Dimensions Citation Indicators

Times Cited: 183

Field Citation Ratio (FCR): 83.77

Relative Citation ratio (RCR): 0.69

Open Access Info