asn_from_list

Create an association using either the command line tool asn_from_list or through the Python API using jwst.associations.asn_from_list.asn_from_list().

Command Line

asn_from_list --help

Usage

Stage 2 Associations

Refer to Stage 2 Associations: Technical Specifications for a full description of Stage 2 associations.

To create a Stage 2 association, use the following command:

asn_from_list -o l2_asn.json -r DMSLevel2bBase *.fits

The -o option defines the name of the association file to create.

The -r DMSLevel2bBase option indicates that a Stage 2 association is to be created.

Each file in the list will have its own product in the association file. When used as input to calwebb_image2 or calwebb_spec2, each product is processed independently, producing the Level 2b result for each product.

For those exposures that require an off-target background or imprint image, modify the members list for those exposure, adding a new member with an exptype of background or imprint as appropriate. The expname for these members are the Level 2a exposures that are the background/imprint to use.

An example product that has both a background and imprint exposure would look like the following:

"products": [
    {
        "name": "jw99999001001_011001_00001_nirspec",
        "members": [
            {
                "expname": "jw99999001001_011001_00001_nirspec_rate.fits",
                "exptype": "science"
            },
            {
                "expname": "jw99999001001_011001_00002_nirspec_rate.fits",
                "exptype": "background"
            },
            {
                "expname": "jw99999001001_011001_00003_nirspec_rate.fits",
                "exptype": "imprint"
            }
        ]
    }
]

Stage 3 Associations

Refer to Stage 3 Associations: Technical Specifications for a full description of Stage 3 associations.

To create a Stage 3 association, use the following command:

asn_from_list -o l3_asn.json --product-name l3_results *.fits

The -o option defines the name of the association file to create.

The --product-name will set the name field that the Stage 3 calibration code will use as the output name. For the above example, the output files created by calwebb_image3, or other Stage 3 pipelines, will all begin with l3_results.

The list of files will all become science members of the association, with the presumption that all files will be combined.

For coronagraphic or AMI processing, set the exptype of the exposures that are the PSF reference exposures to psf. If the PSF files are not in the members list, edit the association and add them as members. An example product with a PSF exposure would look like:

"products": [
    {
        "name": "jw99999-o001_t14_nircam_f182m-mask210r",
        "members": [
            {
                "expname": "jw99999001001_011001_00001_nircam_cal.fits",
                "exptype": "science"
            },
            {
                "expname": "jw99999001001_011001_00002_nircam_cal.fits",
                "exptype": "science"
            },
            {
                "expname": "jw99999001001_011001_00003_nircam_cal.fits",
                "exptype": "psf"
            }
        ]
    }
]

API

asn_from_list() is the main mid-level entry point.

jwst.associations.asn_from_list Module

Create an association from a list.

Functions

asn_from_list(items[, rule])

Create an association from a list.