asn_from_list

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

Command Line

asn_from_list --help

Usage

Level2 Associations

Refer to Level 2 Associations: Technical Specifications for a full description of Level2 associations.

To create a Level2 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 Level2 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 Level2b 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 Level2a exposures the 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"
            }
        ]
    }
]

Level3 Associations

Refer to Level 3 Associations: Technical Specifications for a full description of Level3 associations.

To create a Level3 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 Level3 calibration code will use as the output name. For the example, the output files created by calwebb_image3, or other Level3 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

There are two programmatic entry points: The Main is the highest level entry and is what is instantiated when the command line asn_from_list is used. Main handles the command line interface.

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