Level 2 Associations: Technical Specifications¶
Logical Structure¶
Independent of the actual format, all Level 2 associations have the following structure. Again, the structure is defined and enforced by the Level 2 schema
Top level, or meta, key/values
List of products, each consisting of
Output product name template
List of exposure members, each consisting of
filename of the input exposure
Type of exposure
Errors from the observatory log
Association Candidates this exposure belongs to
Example Association¶
The following example will be used to explain the contents of an association:
{
"asn_rule": "Asn_Lv2Spec",
"asn_pool": "jw82600_001_20160304T145416_pool",
"program": "82600",
"asn_type": "spec2",
"products": [
{
"name": "test_lrs1",
"members": [
{
"expname": "test_lrs1_rate.fits",
"exptype": "science"
}
]
},
{
"name": "test_lrs2bkg",
"members": [
{
"expname": "test_lrs2bkg_rate.fits",
"exptype": "science"
}
]
},
{
"name": "test_lrs2",
"members": [
{
"expname": "test_lrs2_rate.fits",
"exptype": "science"
},
{
"expname": "test_lrs2bkg_rate.fits",
"exptype": "background"
}
]
}
]
}
Association Meta Keywords¶
The following are the top-level, or meta, keywords of an association.
- program optional
Program number for which this association was created.
- asn_type optional
The type of association represented. See Association Types
- asn_id optional
The association id. The id is what appears in the Naming Conventions
- asn_pool optional
Association pool from which this association was created.
- asn_rule optional
Name of the association rule which created this association.
- version_id optional
Version identifier. DMS uses a time stamp with the format
yyyymmddthhmmss
Can be None or NULL- constraints optional
List of constraints used by the association generator to create this association. Format and contents are determined by the defining rule.
products
Keyword¶
A list of products that would be produced by this association. For
Level2, each product is an exposure. Each product should have one
science
member, the exposure on which the Level2b processing will
occur.
Association products have two components:
- name optional
The string template to be used by Level 2b processing tasks to create the output file names. The product name, in general, is a prefix on which the individual pipeline and step modules will append whatever suffix information is needed.
If not specified, the Level2b processing modules will create a name based off the name of the
science
member.- members required
This is a list of the exposures to be used by the Level 2b processing tasks. This keyword is explained in detail in the next section.
members
Keyword¶
members
is a list of objects, each consisting of the following
keywords
- expname required
The exposure file name
- exptype required
Type of information represented by the exposure. Possible values are
science
requiredPrimary science exposure. For each product, only one exposure can be
science
.background
optionalOff-target background exposure to subtract.
imprint
optionalImprint exposure to subtract.
sourcecat
optionalThe catalog of sources to extract spectra for. Usually produced by
calwebb_image3
for wide-field slitless spectroscopy.
Editing the member list¶
As discussed previously, a member is made up of a number of keywords, formatted as follows:
{
"expname": "jw_00003_cal.fits",
"exptype": "science",
},
To remove a member, simply delete its corresponding set.
To add a member, one need only specify the two required keywords:
{
"expname": "jw_00003_cal.fits",
"exptype": "science"
},