# calwebb_ami3: Stage 3 Aperture Masking Interferometry (AMI) Processing¶

Config

calwebb_ami3.cfg

Class

Ami3Pipeline

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.

calwebb_ami3

ami_analyze

ami_average

ami_normalize

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

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

• apply the ami_average step to compute the average of the ami_analyze results for all of the science target exposures, and the average for all of the reference PSF results (if present)

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

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

## Arguments¶

The calwebb_ami3 pipeline has one optional argument:

--save_averages  boolean  default=False


If set to True, the results of the ami_average step will be saved to a file. If not, the results of the ami_average step are passed along in memory to the ami_normalize step.

## Inputs¶

### 2D calibrated images¶

Data model

ImageModel

File suffix

_cal

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 calibrated (“_cal”) products from calwebb_image2 processing.

An example ASN file containing 2 science target and 2 reference PSF target exposures 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": "discover_Asn_AMI",
"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_cal.fits",
"exptype": "psf"
},
{"expname": "jw10005027001_02102_00001_nis_cal.fits",
"exptype": "psf"
},
{"expname": "jw10005004001_02102_00001_nis_cal.fits",
"exptype": "science"
},
{"expname": "jw10005001001_02102_00001_nis_cal.fits",
"exptype": "science"
}
]
}
]
}


## Outputs¶

### Fringe parameter tables¶

Data model

AmiLgModel

File suffix

_ami

For every input exposure, the fringe parameters and closure phases caculated by the ami_analyze step are saved to an “_ami” product file, which is a FITS table containing the fringe parameters and closure phases. Product names use the input “_cal” exposure-based file name, with the association candidate ID included and the product type changed to “_ami”, e.g. “jw93210001001_03101_00001_nis_a0003_ami.fits.”

### Averaged fringe parameters table¶

Data model

AmiLgModel

File suffix

_amiavg or _psf-amiavg

If multiple target or reference PSF exposures are used as input and the “–save_averages” parameter is set to True, the ami_average step will save averaged results for the target in an “_amiavg” product and for the reference PSF in a “_psf-amiavg” product. The file name root will use the source-based output product name given in the ASN file. These files are the same FITS table format as the “_ami” products.

### Normalized fringe parameters table¶

Data model

AmiLgModel

File suffix

_aminorm

If reference PSF exposures are included in the input ASN, the averaged AMI results for the target will be normalized by the averaged AMI results for the reference PSF, via the ami_normalize step, and will be saved to an “_aminorm” product file. This file has the same FITS table format as the “_ami” 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.fits.”