Coronagraphic Data Post-processing Using Projections on Instrumental Modes

Abstract

Directly observing exoplanets with coronagraphs is impeded by the presence of speckles from aberrations in the optical path, which can be mitigated in hardware with wavefront control as well as in post-processing. This work explores using an instrument model in post-processing to separate astrophysical signals from residual aberrations in coronagraphic data. The effect of wavefront error (WFE) on the coronagraphic intensity consists of a linear contribution and a quadratic contribution. When either of the terms is much larger than the other, the instrument response can be approximated by a transfer matrix mapping WFE to detector plane intensity. From this transfer matrix, a useful projection onto instrumental modes that removes the dominant error modes can be derived. We apply this projection to synthetically generated Roman Space Telescope hybrid Lyot coronagraph (HLC) data to extract "robust observables," which can be used instead of raw data for applications such as detection testing. The projection improves planet flux ratio detection limits by about 28% in the linear regime and by over a factor of 2 in the quadratic regime, illustrating that robust observables can increase sensitivity to astrophysical signals and improve the scientific yield from coronagraphic data. While this approach does not require additional information such as observations of reference stars or modulations of a deformable mirror, it can and should be combined with these other techniques, acting as a model-informed prior in an overall post-processing strategy.

arXiv comment19 pages, 10 figures

References in corpus (24)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Angular Differential Imaging: a Powerful High-Contrast Imaging Technique
• Detection and Characterization of Exoplanets and Disks using Projections on Karhunen-Loeve Eigenimages
• A new algorithm for point spread function subtraction in high-contrast imaging: a demonstration with angular differential imaging
• Theoretical Limits on Extrasolar Terrestrial Planet Detection with Coronagraphs
• Imaging Spectroscopy for Extrasolar Planet Detection
• Detection and Characterization of Exoplanets using Projections on Karhunen-Loeve Eigenimages: Forward Modeling
• The Structure of High Strehl Ratio Point-Spread Functions
• Kernel-Phase in Fizeau Inteferometry
• Phase Errors in Diffraction-Limited Imaging: Contrast Limits for Sparse Aperture Masking
• The Nancy Grace Roman Space Telescope Coronagraph Instrument (CGI) Technology Demonstration
• A New Standard for Assessing the Performance of High Contrast Imaging Systems
• Linear and Bayesian Planet Detection Algorithms for the Terrestrial Planet Finder
• Implicit electric field Conjugation: Data-driven focal plane control
• End-to-end numerical modeling of the Roman Space Telescope coronagraph
• Coronagraphic Low Order Wave Front Sensor : post-processing sensitivity enhancer for high performance coronagraphs
• Kernel-phase Detection Limits : Hypothesis Testing and the Example of JWST NIRISS Full Pupil Images
• Kernel Phase and Coronagraphy with Automatic Differentiation
• Wavefront error tolerancing for direct imaging of exo-Earths with a large segmented telescope in space
• Reduced Order Estimation of the Speckle Electric Field History for Space-Based Coronagraphs
• Exoplanet Imaging Data Challenge, phase II: Characterization of exoplanet signals in high-contrast images

Cited by in corpus (1)

• Imaging exoplanets below the telescope stability limit