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

TL;DR

This paper details the design, operation, and initial results of aperture masking interferometry with JWST-NIRISS, enabling high-resolution imaging and kernel phase analysis in space at near-infrared wavelengths.

Contribution

It introduces the NIRISS AMI mode, explains its operational strategies, and presents new data analysis techniques including a user-friendly KPI pipeline for space-based interferometry.

Findings

Successful commissioning of AMI mode on JWST-NIRISS.

Achieved an inner working angle of ~70 mas, smaller than NIRCam's coronagraphs.

Demonstrated the effectiveness of KPI techniques with a new pipeline.

Abstract

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 \micron~wavelengths, and a bright limit of $\simeq 4$ 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 $\simeq 8$ W2 magnitudes. AMI (and KPI) achieve an inner working angle of $\sim 70$ mas that is well inside the $\sim 400$ mas NIRCam inner working angle for its circular occulter coronagraphs at comparable wavelengths.