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Recovery of Diffraction-Limited Object Autocorrelations from Astronomical Speckle Interferograms using the CLEAN Algorithm

Gorham, P. W. and Ghez, A. M. and Haniff, C. A. and Prince, T. A. (1990) Recovery of Diffraction-Limited Object Autocorrelations from Astronomical Speckle Interferograms using the CLEAN Algorithm. Astronomical Journal, 100 (1). pp. 294-306. ISSN 0004-6256. doi:10.1086/115515.

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We present a new technique for processing speckle interferometric data is presented, which uses the CLEAN algorithm, originally developed for the removal of the effects of incomplete spatial frequency coverage in aperture synthesis radio maps. Since Labeyrie first noted in 1970 that the autocorrelation of a speckle-gram preserves information up to the diffraction limit of an optical telescope, a number of different techniques have been applied to recover this information, usually by Fourier deconvolution of the average power spectrum of the specklegrams with a similar spectrum for a known point source. An alternative is to deconvolve the average autocorrelation of the specklegrams directly, rather than the power spectrum; this is where CLEAN, which has been shown to be a powerful tool in deconvolution problems, may be used. Also, because of the immunity of CLEAN to gaps in the spatial frequency coverage of the power spectrum, deconvolution is robust under conditions where regions of low signal-to-noise ratio i the raw speckle data effectively introduce such gaps. We find that CLEAN is straightforward to apply, and yields results that exceed the quality of recoveries made using at least one other existing technique. Diffraction-limited and near-diffraction-limited results are presented, using photon-noise-limited specklegrams taken with the Hale 5-m telescope at Palomar under a variety of seeing conditions.

Item Type:Article
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URLURL TypeDescription
Ghez, A. M.0000-0003-3230-5055
Prince, T. A.0000-0002-8850-3627
Additional Information:Copyright 1990, American Astronomical Society. Received 10 April 1989; revised 26 March 1990. We thank the W. M. Keck Foundation for their financial support, the Concurrent Computing Center at Caltech for providing the NCUBE computer time for data reductio, and S. Kulkarni, T. Nakajima, G. Neugebauer, and A. Readhead for useful discussion and comments. We also thank R. Cook, G. Smith, A. Lee, and the staff of Palomar Observatory for their invaluable help with the hardware and observations. This work was supported in part by DOE Grant No. DE-FG03-85ER25009 and NSF Grant No. AST8351736.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Department of Energy (DOE)DE-FG03-85ER25009
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1990-17
Issue or Number:1
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45634
Deposited By: Deborah Miles
Deposited On:09 May 2014 17:28
Last Modified:10 Nov 2021 17:14

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