23 research outputs found
The Near Infrared Imager and Slitless Spectrograph for the James Webb Space Telescope. IV. Aperture Masking Interferometry
No full textThe 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 mag 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 (4.6 μm) magnitudes. AMI NRM and KPI achieve an inner working angle of ∼70 mas, which is well inside the ∼400 mas NIRCam inner working angle for its circular occulter coronagraphs at comparable wavelengths
Data analysis tools for exoplanet imaging with JWST
No full textIn this poster, we present multiple tools to simulate, reduce, and analyze JWST data. We developed NIRCCoS, a NIRCam coronagraphy image simulator based on the powerful pyNRC package, as well as spaceKLIP, which enables using pyKLIP PSF subtraction for JWST NIRCam and MIRI images. Furthermore, we developed a kernel phase stage 3 pipeline for JWST NIRCam and NIRISS data which can be interfaced in the same way as the official JWST stage 3 pipelines for e.g. coronagraphy and the fouriever toolkit, which enables analysis of various kinds of interferometric data
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Performance of Near-Infrared High-Contrast Imaging Methods with JWST from Commissioning
No full textThe James Webb Space Telescope (JWST) will revolutionize the field of high-contrast imaging and enable both the direct detection of Saturn-mass planets and the characterization of substellar companions in the mid-infrared. While JWST will feature unprecedented sensitivity, angular resolution will be the key factor when competing with ground-based telescopes. Here, we aim to characterize the performance of several extreme angular resolution imaging techniques available with JWST in the 3-5 µm regime based on data taken during the instrument commissioning. Firstly, we introduce custom tools to simulate, reduce, and analyze JWST NIRCam and MIRI coronagraphy data and use these tools to extract companion detection limits from on-sky NIRCam round and bar mask coronagraphy observations. Secondly, we present on-sky JWST NIRISS aperture masking interferometry (AMI) and kernel phase imaging (KPI) observations from which we extract companion detection limits using the publicly available fouriever tool. Scaled to a total integration time of one hour and a target of the brightness of AB Dor (W1 ≈ 4.4 mag, W2 ≈ 3.9 mag), we find that NIRISS AMI and KPI reach contrasts of ∼ 7-8 mag at ∼ 70 mas and ∼ 9 mag at ∼ 200 mas. Beyond ∼ 250 mas, NIRCam coronagraphy reaches deeper contrasts of ∼ 13 mag at ∼ 500 mas and ∼ 15 mag at ∼ 2 arcsec. While the bar mask performs ∼ 1 mag better than the round mask at small angular separations ≲ 0.75 arcsec, it is the other way around at large angular separations ≳ 1.5 arcsec. Moreover, the round mask gives access to the full 360 deg field-of-view which is beneficial for the search of new companions. We conclude that already during the instrument commissioning, JWST high-contrast imaging in the L- and M-bands performs close to its predicted limits and is a factor of ∼ 10 times better at large separations than the best ground-based instruments operating at similar wavelengths despite its \u3e 2 times smaller collecting area
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems III: Aperture Masking Interferometric Observations of the star HIP 65426 at 3.8 μm
No full textThe James Webb Interferometer: Space-based interferometric detections of PDS 70 b and c at 4.8 m
No full textWe observed the planet-hosting system PDS 70 with the James Webb Interferometer, JWST\u27s Aperture Masking Interferometric (AMI) mode within NIRISS. Observing with the F480M filter centered at 4.8 m, we simultaneously fit geometrical models to the outer disk and the two known planetary companions. We re-detect the protoplanets PDS 70 b and c at an SNR of 14.7 and 7.0, respectively. Our photometry of both PDS 70 b and c provides tentative evidence of mid-IR circumplanetary disk emission through fitting SED models to these new measurements and those found in the literature. We also newly detect emission within the disk gap at an SNR of 4, at a position angle of degrees, and an unconstrained separation within 200 mas. Follow-up observations will be needed to determine the nature of this emission. We place a 5 upper limit of 208 10 Jy on the flux of the candidate PDS 70 d at 4.8 m, which indicates that if the previously observed emission at shorter wavelengths is due to a planet, this putative planet has a different atmospheric composition than PDS 70 b or c. Finally, we place upper limits on emission from any additional planets in the disk gap. We find an azimuthally averaged 5 contrast upper limit 7 magnitudes at separations greater than 110 mas. These are the deepest limits to date within 250 mas at 4.8 m and the first space-based interferometric observations of this system.Accepted for publication in A
The James Webb Interferometer: Space-based Interferometric Detections of PDS 70 b and c at 4.8 μm
No full textWe observed the planet-hosting system PDS 70 with the James Webb Interferometer, JWST's aperture masking interferometric mode within NIRISS. Observing with the F480M filter centered at 4.8 mu m, we simultaneously fit geometrical models to the outer disk and the two known planetary companions. We redetect the protoplanets PDS 70 b and c at a signal-to-noise ratio (SNR) of 14.7 and 7.0, respectively. Our photometry of both PDS 70 b and c provides tentative evidence of mid-IR circumplanetary disk emission through fitting spectral energy distribution models to these new measurements and those found in the literature. We also newly detect emission within the disk gap at an SNR of similar to 4, a position angle of 220-15+10 @, and an unconstrained separation within similar to 200 mas. Follow-up observations will be needed to determine the nature of this emission. We place a 5 sigma upper limit of 208 +/- 10 mu Jy on the flux of the candidate PDS 70 d at 4.8 mu m, which indicates that if the previously observed emission at shorter wavelengths is due to a planet, this putative planet has a different atmospheric composition than PDS 70 b or c. Finally, we place upper limits on emission from any additional planets in the disk gap. We find an azimuthally averaged 5 sigma contrast upper limit >7 mag at separations greater than 110 mas. These are the deepest limits to date within similar to 250 mas at 4.8 mu m and the first space-based interferometric observations of this system
