The calwebb_ami3 module is stage 3 of the JWST Science Calibration Pipeline for NIRISS aperture masking interferometry (AMI) data. The inputs to this stage are the calibrated slope images (calwebb_image2 output) and the output is fringe parameters. The steps are listed in Figure 1 with the flow from the top to the bottom.

Unless otherwise stated, the algorithms described are the baseline version.

A brief description of each of the steps within calwebb_ami3 can be found below, along with links to further details (e.g., the relevant reference files) that can be found on the corresponding ReadTheDocs pages. Note, however, that the reference files themselves are all provided via CRDS. For instrument mode-specific notes on these pipeline steps see the corresponding known issues with JWST data articles.

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Assemble reference PSFs

The available list of reference PSFs is generated. These reference PSFs consist of reference stars specifically observed for the target. Note that this step is in practice taken care of by the association generator, which lists all science and PSF reference inputs to be used by calwebb_ami3 processing.

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Calculate fringe parameters

ReadTheDocs documentation: AMI Analyze
Package name: ami_analyze

The closure phases and visibilities for each reference PSF and target are calculated. As part of this calculation, the centers of the reference and target PSFs are determined (iteratively).

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Average fringe parameters

ReadTheDocs documentation: AMI Average 
Package name: ami_average

Averaging the fringe parameters taken over multiple exposures improves the signal to noise of the measurements. The averaging is done for both the target and reference PSF observations.

Final fringe parameters

ReadTheDocs documentation: AMI Normalize 
Package name: ami_normalize

The reference PSF closure phases are subtracted from the target closure phases. The target visibilities are divided by the reference PSF visibilities. These two calculations are done matched by dither position.

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