Data Product Specification¶

For an introductory high-level overview of how data products are created see section Data Product Creation.

The Data Product Specification is the primary input to daqDpmMerge and describes how the final Data Product is created. All source files referenced in the specification must be locally accessible and relative paths are relative to a single root path which is either the directory containing the specification or an explicit root directory passed as an option to daqDpmMerge.

Merging can be done by creating a new file or to merge in-place. If no FITS file target is specified using the property target/source described below, then a new empty file will be created automatically into which the sources will be added.

Note

It is expected that daqDpmMerge will validate keywords against a set of keyword dictionaries.

Primary HDU keywords¶

There are two types of sources for primary HDU keywords:

Keywords in JSON format.

These keywords were provided directly to daqOcmServer using the available APIs. These keywords are defined by the named JSON object FitsKeywordsSource.
Keywords copied from source FITS files.

Which keywords from the source primary HDU to copy to the target primary HDU are derived using the keyword rules specified in the source.

All these keywords will be merged together:

Value Keywords and ESO Keywords keyword collisions are resolved by keeping the keyword from highest priority source.
Commentary Keywords are appended in source priority order.

And then by default sorted as specified by DICD [RD1](section 3.1.1.3):

Value keywords are sorted by source order:

The individual order of value keywords from the same source (file or list of keywords) is kept to not reorder keywords that belong together. For example it make sense to keep RA and DEC together:
OBJECT  = 'karma_cdfs_8_LP.cat' / Original target.
RA      =        53.087446 / [deg] 03:32:20.9 RA (J2000) pointing
DEC     =        -27.84692 / [deg] -27:50:48.9 DEC (J2000) pointing
Rather than e.g. sorting alphabetically:
DEC     =        -27.84692 / [deg] -27:50:48.9 DEC (J2000) pointing
OBJECT  = 'karma_cdfs_8_LP.cat' / Original target.
RA      =        53.087446 / [deg] 03:32:20.9 RA (J2000) pointing

ESO hierarchical keywords are sorted by:
1. Category1 (DPR, OBS, TPL, GEN, TEL, ADA, INS, DET, any other)
2. Keyword name in alphabetic order.

1: Category in an ESO hierarchical keyword is the first token in the logical keyword name. The category is TEL in the logical keyword name TEL MOON RA. See also glossary ESO Keyword.

HDU Extensions¶

The FITS HDU extensions are merged in order of descending priority:

Extensions from the in-place target, if any.
Extensions from other source files.

The source files in attribute sources are specified in descending priority. Like keywords the relative order between extensions in the same file is kept.

JSON Description¶

See Data Product Specification Schema for detailed specifciation.