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Title: iPTF search for an optical counterpart to gravitational-wave transient GW150914

The intermediate Palomar Transient Factory (iPTF) autonomously responded to and promptly tiled the error region of the first gravitational-wave event GW150914 to search for an optical counterpart. Only a small fraction of the total localized region was immediately visible in the northern night sky, due both to Sun-angle and elevation constraints. Here, we report on the transient candidates identified and rapid follow-up undertaken to determine the nature of each candidate. Even in the small area imaged of 126 deg 2, after extensive filtering, eight candidates were deemed worthy of additional follow-up. Within two hours, all eight were spectroscopically classified by the Keck II telescope. Curiously, even though such events are rare, one of our candidates was a superluminous supernova. We obtained radio data with the Jansky Very Large Array and X-ray follow-up with the Swift satellite for this transient. None of our candidates appear to be associated with the gravitational-wave trigger, which is unsurprising given that GW150914 came from the merger of two stellar-mass black holes. In conclusion, this end-to-end discovery and follow-up campaign bodes well for future searches in this post-detection era of gravitational waves.
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  1. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  2. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland, College Park, MD (United States)
  3. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  4. Texas Tech Univ., Lubbock, TX (United States)
  5. Inter-Univ. Centre for Astronomy and Astrophysics (IUCAA), Pune (India)
  6. Stockholm Univ., Stockholm (Sweden)
  7. National Radio Astronomy Observatory, Socorro, NM (United States)
  8. Weizmann Institute of Science, Rehovot (Israel)
  9. Lockheed Martin Space Systems Co., Palo Alto, CA (United States)
  10. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  11. Niels Bohr Institute, Copenhagen (Denmark)
  12. San Diego State Univ., San Diego, CA (United States); The Univ. of Tokyo, Chiba (Japan)
  13. Max Planck Institute for Astonomy, Heidelberg (Germany)
  14. Univ. of Wisconsin, Milwaukee, WI (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
The Astrophysical Journal. Letters
Additional Journal Information:
Journal Volume: 824; Journal Issue: 2; Journal ID: ISSN 2041-8213
Institute of Physics (IOP)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; gravitational waves; methods: observational; techniques: spectroscopic; surveys
OSTI Identifier: