First faint Dual-Field Phase-Referenced observations on the Keck Interferometer

J. Woillez, P. Wizinowich, R. Akeson, M. Colavita, J. Eisner, R. Millan-Gabet, J. Monnier, J. U. Pott, S. Ragland, E. Appleby, A. Cooper, C. Felizardo, J. Herstein, O. Martin, D. Medeiros, D. Morrison, T. Panteleeva, B. Smith, K. Summers, K. TsubotaC. Tyau, E. Wetherell

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Ground-based long baseline interferometers have long been limited in sensitivity by the short integration periods imposed by atmospheric turbulence. The first observation fainter than this limit was performed on January 22, 2011 when the Keck Interferometer observed a K=11.5 target, about one magnitude fainter than its K=10.3 limit. This observation was made possible by the Dual Field Phase Referencing instrument of the ASTRA project: simultaneously measuring the real-time effects of the atmosphere on a nearby bright guide star, and correcting for it on the faint target, integration time longer than the turbulence time scale are made possible. As a prelude tóthis demonstration, we first present the implementation of Dual Field Phase Referencing on the interferometer. We then detail its on-sky performance focusing on the accuracy of the turbulence correction, and on the resulting fringe contrast stability. We conclude with a presentation of early results obtained with Laser Guide Star AO and the interferometer.

Original languageEnglish (US)
Title of host publicationOptical and Infrared Interferometry III
StatePublished - 2012
EventOptical and Infrared Interferometry III - Amsterdam, Netherlands
Duration: Jul 1 2012Jul 6 2012

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


OtherOptical and Infrared Interferometry III


  • Dual field phase referencing
  • Laser guide star adaptive optics
  • Optical long baseline interferometry

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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