Algorithms for calwebb_ami3, which is stage 3 of the JWST Science Calibration Pipeline for NIRISS Aperture Masking Interferometry (AMI) are used to process data from calibrated slope images to fringe parameters.
Words in bold are GUI menus/
panels or data software packages;
bold italics are buttons in GUI
tools or package parameters.
Unless otherwise stated, the algorithms described are the baseline version.
Steps for all AMI data
Assemble reference PSFs
The available list of reference PSFs is generated. These reference PSFs consist of reference stars specifically observed for the target.
Calculate fringe parameters
Software documentation outside JDox: 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).
Average fringe parameters
Software documentation outside JDox: 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
Software documentation outside JDox: 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 2 calculations are done matched by dither position.