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Proceedings Paper

Water vapor measurement and compensation in the near- and mid-infrared with the Keck Interferometer Nuller
Author(s): Chris Koresko; M. Mark Colavita; Eugene Serabyn; Andrew Booth; Jean Garcia
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Paper Abstract

Water vapor is the dominant source of randomly-changing atmospheric dispersion on timescales of seconds to minutes in the near- and mid-infrared. The dispersion changes are sufficient to limit the performance of the Keck Nuller unless steps are taken to measure and compensate for them. Here we present the first measurements of water vapor differential column fluctuations with the mid-infrared Keck Nuller and its near-infrared fringe tracker, taken in October 2005, and discuss theoretical and practical aspects of our dispersion feedforward implementation. The data show much larger fluctuations than were seen in median Mauna Kea conditions measured at radio wavelengths, and probably account for the generally poor performance of the Nuller during the observing run. The measurements in the two bands show strong correlations, indicating that the planned feedforward of the near-infrared value to stabilize the dispersion in the mid-infrared will substantially reduce the residual dispersion fluctuations seen by the Nuller.

Paper Details

Date Published: 28 June 2006
PDF: 8 pages
Proc. SPIE 6268, Advances in Stellar Interferometry, 626817 (28 June 2006); doi: 10.1117/12.672434
Show Author Affiliations
Chris Koresko, Michelson Science Ctr., California Institute of Technology (United States)
M. Mark Colavita, Jet Propulsion Lab. (United States)
Eugene Serabyn, Jet Propulsion Lab. (United States)
Andrew Booth, Jet Propulsion Lab. (United States)
Jean Garcia, Jet Propulsion Lab. (United States)

Published in SPIE Proceedings Vol. 6268:
Advances in Stellar Interferometry
John D. Monnier; Markus Schöller; William C. Danchi, Editor(s)

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