GPI PSF subtraction with TLOCI: the next evolution in exoplanet/disk high-contrast imaging

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1117/12.2055245
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Name affiliation
  1. National Research Council of Canada. National Science Infrastructure
  2. National Research Council of Canada
FormatText, Article
Proceedings titleAdaptive Optics Systems IV
Series titleProceedings of SPIE; no. 9148
ConferenceAdaptive Optics Systems IV, June 22-27, 2014
ISSN0277-786X
1996-756X
ISBN9780819496164
Article number91480U
SubjectAlgorithms; Extrasolar planets; Optical transfer function; Signal to noise ratio; Stars; Circumstellar disks; High contrast imaging; Image subtraction; Integral Field Unit; Optimized combinations; Polychromatic images; Reference image; Rotated images; Adaptive optics
Abstract
To directly image exoplanets and faint circumstellar disks, the noisy stellar halo must be suppressed to a high level. To achieve this feat, the angular differential imaging observing technique and the least-squares Locally Optimized Combination of Images (LOCI) algorithm have now become the standard in single band direct imaging observations and data reduction. With the development and commissioning of new high-order high-contrast adaptive optics equipped with integral field units, the image subtraction algorithm needs to be modified to allow the optimal use of polychromatic images, field-rotated images and archival data. A new algorithm, TLOCI (for Template LOCI), is designed to achieve this task by maximizing a companion signal-to-noise ratio instead of simply minimizing the noise as in the original LOCI algorithm. The TLOCI technique uses an input spectrum and template Point Spread Functions (PSFs, generated from unocculted and unsaturated stellar images) to optimize the reference image least-squares coefficients to minimize the planet self-subtraction, thus maximizing its throughput per wavelength, while simultaneously providing a maximum suppression of the speckle noise. The new algorithm has been developed using on-sky GPI data and has achieved impressive contrast. This paper presents the TLOCI algorithm, on-sky performance, and will discuss the challenges in recovering the planet spectrum with high fidelity.
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PublisherSPIE
LanguageEnglish
Peer reviewedYes
NPARC number21275497
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