Palomar Testbed Interferometer & Keck Interferometer

M. Mark Colavita (Jet Propulsion Laboratory)

Abstract:

With long baseline interferometers, narrow-angle astrometric measurements can be made from the ground with sufficient accuracy for science programs such as the search for extra-solar planets. The Palomar Testbed Interferometer (PTI) and the Keck Interferometer share a common architecture for conducting these measurements. Dual-star modules close to the telescopes select target and reference stars and feed their light to a central beam combiner containing delay lines and fringe detectors. One fringe detector tracks the bright target star, stabilizing atmospheric motion to allow long synthetic integrations times with the second fringe detector on the faint reference star. End-to-end laser metrology with an accurate model of the narrow-angle baseline allow conversion of delay differences to angles on the sky.

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References:

• The Palomar Testbed Interferometer
  M.M. Colavita et al.,
  Astrophys. J. 510, 505 (1999).

• Keck Interferometer: progress report
  M. M. Colavita and P. L. Wizinowich
  Proc. SPIE 4006, 310 (2000).