M. M. Kasliwal, S. B. Cenko, L. P. Singer, A. Corsi, Y. Cao, T. Barlow, V. Bhalerao, E. Bellm, D. Cook, G. E. Duggan, R. Ferretti, D. A. Frail, A. Horesh, R. Kendrick, S. R. Kulkarni, R. Lunnan, N. Palliyaguru, R. Laher, F. Masci, I. ManulisA. A. Miller, P. E. Nugent, D. Perley, T. A. Prince, R. M. Quimby, J. Rana, U. Rebbapragada, B. Sesar, A. Singhal, J. Surace, A. Van Sistine

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


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 deg2, 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. This end-to-end discovery and follow-up campaign bodes well for future searches in this post-detection era of gravitational waves.

Original languageAmerican English
Article numberL24
JournalAstrophysical Journal Letters
Issue number2
StatePublished - 20 Jun 2016
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2016. The American Astronomical Society. All rights reserved..


  • gravitational waves
  • methods: observational
  • surveys
  • techniques: spectroscopic


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