Angular differential kernel phases

Laugier, R.; Martinache, Frantz; Cvetojevic, Nick; Mary, David; Ceau, Alban; N’Diaye, Mamadou; Kammerer, Jens; Lozi, Julien; Guyon, Olivier; Lopez, Coline

doi:10.1051/0004-6361/201937121

Cited by 10 publications

(9 citation statements)

References 14 publications

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“…Furthermore, the reduced χ 2 of our binary model fits is larger than one, meaning that we are underestimating the errors. This is in agreement with previous studies that have shown that the kernel phase technique is dominated by systematic errors, usually yielding a reduced χ 2 between ∼ 1-10 ( Martinache et al 2020;Laugier et al 2020;Kammerer et al 2019;Ireland 2013).…”

Section: Binary Model Fitssupporting

confidence: 93%

Mid-infrared photometry of the T Tauri triple system with kernel phase interferometry

Kammerer

Kasper

Ireland

et al. 2021

A&A

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Context. T Tauri has long been the prototypical young pre-main-sequence star. However, with increasing resolution and sensitivity, T Tauri has now been decomposed into a triple system with a complex disk and outflow geometry. Aims. We aim to measure the brightness of all three components of the T Tauri system (T Tau N, T Tau Sa, and T Tau Sb) in the mid-infrared in order to obtain photometry around the ∼9.7 μm silicate feature. This allows us to study their variability and to investigate the distribution of dust and the geometry of circumstellar and circumbinary disks in this complex system. Methods. We observe the T Tauri system with the Very Large Telescope (VLT)/VISIR-NEAR instrument, performing diffraction-limited imaging in the mid-infrared. With kernel phase interferometry post-processing of the data, and using the astrometric positions of all three components from VLT/SPHERE, we measure the three components’ individual brightnesses (including the southern binary at an angular separation down to ∼0.2λ/D) and obtain their photometry. In order to validate our methods, we simulate and recover mock data of the T Tauri system using the observed reference point-spread function of HD 27639. Results. We find that T Tau N is rather stable and shows weak silicate emission, while T Tau Sa is highly variable and shows prominent silicate absorption. T Tau Sb became significantly fainter compared to data from 2004 and 2006, suggesting increased extinction by dust. The precision of our photometry is limited by systematic errors in kernel phase interferometry, which is consistent with previous studies using this technique. Conclusions. Our results confirm the complex scenario of misaligned disks in the T Tauri system that had been observed previously, and they are in agreement with the recently observed dimming of T Tau Sb in the near-infrared. Our mid-infrared photometry supports the interpretation that T Tau Sb has moved behind the dense region of the Sa-Sb circumbinary disk on its tight orbit around Sa, therefore suffering increased extinction.

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Section: Binary Model Fitssupporting

confidence: 93%

Mid-infrared photometry of the T Tauri triple system with kernel phase interferometry

Kammerer

Kasper

Ireland

et al. 2021

A&A

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“…Later, Kammerer et al (2019) and Wallace et al (2020) conducted the first KPI surveys for young self-luminous companions at small angular separations which are inaccessible with classical coronagraphy techniques. At the same time, Laugier et al (2019) developed methods to apply the KPI technique to saturated images and also introduced angular differential kernels (Laugier et al 2020) which take advantage of the angular diversity of ground-based pupil tracking mode data to selfcalibrate kernel phase observables. The CLEARP pupil mask enables full pupil images using AMI filters, target acquisition, and fast readout subarray.…”

Section: Kernel Phase Interferometrymentioning

confidence: 99%

The Near Infrared Imager and Slitless Spectrograph for the James Webb Space Telescope -- IV. Aperture Masking Interferometry

Sivaramakrishnan¹,

Tuthill²,

Lloyd³

et al. 2022

Preprint

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The James Webb Space Telescope's Near Infrared Imager and Slitless Spectrograph (JWST-NIRISS) flies a 7-hole non-redundant mask (NRM), the first such interferometer in space, operating at 3-5 µm wavelengths, and a bright limit of 4 magnitudes in W2. We describe the NIRISS Aperture Masking Interferometry (AMI) mode to help potential observers understand its underlying principles, present some sample science cases, explain its operational observing strategies, indicate how AMI proposals can be developed with data simulations, and how AMI data can be analyzed. We also present key results from commissioning AMI. Since the allied Kernel Phase Imaging (KPI) technique benefits from AMI operational strategies, we also cover NIRISS KPI methods and analysis techniques, including a new user-friendly KPI pipeline. The NIRISS KPI bright limit is 8 W2 magnitudes. AMI (and KPI) achieve an inner working angle of ∼ 70 mas that is well inside the ∼ 400 mas NIRCam inner working angle for its circular occulter coronagraphs at comparable wavelengths.

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“…This is likewise an issue where detector nonlinearity and saturation significantly distort the PSF. While the analytic series expansion is no longer applicable in these regimes, using matrix Fourier transforms and skipping saturated pixels or pixels inside the coronagraphic inner working angle has shown promise for pushing kernel phase beyond its conventional limitations (Laugier & Martinache 2019), as have generalizations that exploit angular differential imaging for a further level of calibration (Laugier et al 2020).…”

Section: Complex Optical Systems: Nullers and Coronagraphsmentioning

confidence: 99%

Kernel Phase and Coronagraphy with Automatic Differentiation

Pope,

Pueyo,

Xin

et al. 2020

Preprint

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The accumulation of aberrations along the optical path in a telescope produces distortions and speckles in the resulting images, limiting the performance of cameras at high angular resolution. It is important to achieve the highest possible sensitivity to faint sources, using both hardware and data analysis software. While analytic methods are efficient, real systems are better modelled numerically, but numerical models of complicated optical systems with many parameters can be hard to understand, optimize and apply. Automatic differentiation or 'backpropagation' software developed for machine learning applications now makes calculating derivatives with respect to aberrations in arbitrary planes straightforward for any optical system. We apply this powerful new tool to the problem of high-angular-resolution astronomical imaging. Self-calibrating observables such as the 'closure phase' or 'bispectrum' have been widely used in optical and radio astronomy to mitigate optical aberrations and achieve high fidelity imagery. Kernel phases are a generalization of closure phases valid in the limit of small phase errors. Using automatic differentiation, we reproduce existing kernel phase theory within this framework and demonstrate an extension to the case of a Lyot coronagraph, which is found to have self-calibrating combinations of speckles which are resistant to phase noise, but only in the very high wavefront quality regime. As an illustrative example, we reanalyze Palomar adaptive optics observations of the binary α Ophiuchi, finding consistency between the new pipeline and the existing standard. We present a new Python package morphine that incorporates these ideas, with an interface similar to the popular package poppy, for

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Angular differential kernel phases

Cited by 10 publications

References 14 publications

Mid-infrared photometry of the T Tauri triple system with kernel phase interferometry

Mid-infrared photometry of the T Tauri triple system with kernel phase interferometry

The Near Infrared Imager and Slitless Spectrograph for the James Webb Space Telescope -- IV. Aperture Masking Interferometry

Kernel Phase and Coronagraphy with Automatic Differentiation

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