calwebb_ami3: Stage 3 Aperture Masking Interferometry (AMI) Processing





The stage 3 AMI pipeline is applied to associations of calibrated NIRISS AMI exposures. It computes fringe parameters for individual exposures, averages the fringe results from multiple exposures, and, optionally, corrects science target fringe parameters using the fringe results from reference PSF targets. The steps applied by the calwebb_ami3 pipeline are shown below.




When given an association file as input, which lists multiple science target and reference PSF exposures, the pipeline will:

  1. apply the ami_analyze step to each input exposure independently, computing fringe parameters for each

  2. apply the ami_normalize step to correct the science target results using the reference PSF results (if present)

If no reference PSF target exposures are present in the input ASN file, the ami_normalize step is skipped.


The calwebb_ami3 pipeline does not currently use any optional arguments.


3D calibrated images

Data model:


File suffix:


The inputs to calwebb_ami3 need to be in the form of an ASN file that lists multiple science target exposures, and optionally reference PSF exposures as well. The individual exposures must be in the form of 3D calibrated (“_calints”) products from calwebb_image2 processing.

An example ASN file containing one science target and one reference PSF target exposure is shown below. Only 1 product is defined, corresponding to the science target, with members consisting of exposures for both the science target and the reference PSF target, as indicated by the “exptype” values for each.

{"asn_type": "ami3",
 "asn_rule": DMS_Level3_Base",
 "program": "10005",
 "asn_id": "a3001",
 "target": "t001",
 "asn_pool": "jw10005_001_01_pool",
 "products": [
     {"name": "jw10005-a3001_t001_niriss_f277w-nrm",
      "members": [
          {"expname": "jw10005007001_02102_00001_nis_calints.fits",
           "exptype": "psf"
          {"expname": "jw10005004001_02102_00001_nis_calints.fits",
           "exptype": "science"


Interferometric observables

Data model:


File suffix:


For every input exposure, the fringe parameters and closure phases calculated by the ami_analyze step are saved to an “_ami-oi.fits” product file, which is a FITS table of median observables over all integrations of the input file. Product names use the input “_calints” exposure-based file name, with the association candidate ID included and the product type changed to “_ami-oi.fits”, e.g. “jw93210001001_03101_00001_nis_a0003_ami-oi.fits.”

Normalized Interferometric Observables

Data model:


File suffix:


If reference PSF exposures are included in the input ASN, the AMI results for the target will be normalized by the AMI results for the reference PSF, via the ami_normalize step, and will be saved to an “_aminorm-oi.fits” product file. This file has the same FITS table format as the “_ami-oi.fits” products. The file name root uses the source-based output product name given in the ASN file, e.g. “jw93210-a0003_t001_niriss_f480m-nrm_aminorm-oi.fits.”