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Lucky imaging and speckle discrimination for the detection of faint companions with adaptive optics

Gladysz, Szymon and Christou, Julian and Law, Nicholas and Dekany, Richard and Redfern, Michael and Mackay, Craig (2008) Lucky imaging and speckle discrimination for the detection of faint companions with adaptive optics. In: Adaptive Optics Systems. Proceedings of SPIE. No.7015. Society of Photo-Optical Instrumentation Engineers , Bellingham, WA, Art. No. 70152H. ISBN 9780819472250.

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We have analyzed the application of frame selection ("lucky imaging") to adaptive optics (AO), short-exposure observations of faint companions. We have used the instantaneous Strehl ratio as an image quality metric. The probability density function (PDF) of this quantity can be used to determine the outcome of frame selection in terms of optimizing the Strehl ratio and the peak-signal-to-noise-ratio of the shift-and-add image. In the presence of static speckles, frame selection can lead to both: improvement in resolution--as quantified by the Strehl ratio, as well as faint signal detectability--given by the peak-signal-to-noise-ratio. This theoretical prediction is confirmed with real data from AO observations using Lick Observatory's 3m Shane telescope, and the Palomar Observatory's 5m Hale telescope. In addition, we propose a novel statistics-based technique for the detection of faint companions from a sequence of AO-corrected exposures. The algorithm, which we call stochastic speckle discrimination, utilizes the "statistical signature" of the centre of the point spread function (PSF) to discriminate between faint companions and static speckles. The technique yields excellent results even for signals invisible in the shift-and-add images.

Item Type:Book Section
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Law, Nicholas0000-0001-9380-6457
Additional Information:© 2008 Society of Photo-Optical Instrumentation Engineers. This research was supported by Science Foundation Ireland under Grants 02/PI.2/039C and 07/IN.1/I906, as well as the National Science Foundation Science and Technology Center for Adaptive Optics, which is managed by the University of California at Santa Cruz under cooperative agreement AST 98-76783. We would like to thank the staff of Lick Observatory, in particular Elinor Gates and Bryant Grigsby. In addition we would like to thank Michael Fitzgerald for information about the high-speed mode of the IRCAL camera, and Chris Dainty for support for this research.
Funding AgencyGrant Number
Science Foundation, Ireland02/PI.2/039C
Science Foundation, Ireland07/IN.1/I906
NSFAST 98-76783
Subject Keywords:adaptive optics, image processing, astronomy, faint companions, exoplanets
Series Name:Proceedings of SPIE
Issue or Number:7015
Record Number:CaltechAUTHORS:20181217-135626281
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Official Citation:Szymon Gladysz, Julian Christou, Nicholas Law, Richard Dekany, Michael Redfern, Craig Mackay, "Lucky imaging and speckle discrimination for the detection of faint companions with adaptive optics," Proc. SPIE 7015, Adaptive Optics Systems, 70152H (10 July 2008); doi: 10.1117/12.788442
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91869
Deposited By: Tony Diaz
Deposited On:18 Dec 2018 19:13
Last Modified:16 Nov 2021 03:44

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