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Speckle Space-Time Covariance in High-Contrast Imaging

Presentation #430.04 in the session Exoplanet Direct Imaging.

Published onJun 29, 2022
Speckle Space-Time Covariance in High-Contrast Imaging

We introduce a new framework for point-spread function (PSF) subtraction based on the spatio-temporal variation of speckle noise in high contrast imaging data where the sampling timescale is faster than the speckle evolution timescale. Space-time covariance arises in the pupil as atmospheric layers translate across the telescope aperture and create small, time-varying perturbations in the phase of the incoming wavefront. The propagation of this field to the focal plane preserves some of that space-time covariance. To utilize this covariance, our new approach uses a Karhunen-Loeve transform on a set of image sequences, as opposed to a set of single reference images as in previous implementations of Karhunen-Loeve Image Processing (KLIP) for high-contrast imaging. With the recent development of photon counting detectors, such as microwave kinetic inductance detectors (MKIDs), this technique now has the potential to improve contrast when used as a post-processing step. Preliminary testing on simulated data shows this technique improves contrast, but further gains may be realized with further improvements to the technique.

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