Add metadata to reference parent data products |
On this page... |
Establishing the provenance of science data products is important to the users of HLSP collections for a number of reasons, including:
Provenance should be recorded in multiple ways, including the Project Description file and the README file that must be included in every HLSP collection (see Required Contents). It is also established in the primary journal paper where each HLSP collection is described. Various of the metadata listed in this chapter as required or recommended partially address these needs. The focus of this article is the recording of sufficient metadata that associations can be created between HLSP products and the MAST mission products (or the products from other observatories) from which they were derived. Two approaches have been used for this purpose, as described in the subsections below.
The other sections of this chapter identified some keywords where the value in the contributing products may be different. To represent a meaningful value in the HLSP product:
The following table illustrates the concept for a composite UV spectrum of a target, using two HST instruments. Note that the contributing observations are linked to the HLSP product through the MAST Observation ID, shown in the table as 'FILEID
nn'.
Keyword | Value |
---|---|
DISPERSR | 'MULTI' |
DISPER01 | 'G130M/180' |
DISPER02 | 'E230M' |
FILEID01 | 'lea22cx3q' |
FILEID02 | 'ockp07020' |
INSTRUME | 'MULTI' |
INSTRU01 | 'COS' |
INSTRU02 |
|
An acceptable synonym for |
It is sometimes tedious, even impractical, to record critical metadata for every data product that contributed to constructing an HLSP product. Examples include:
In these cases it may be better to collect this information in a BINTABLE extension to each HLSP FITS product. The table should have the following attributes:
EXTNAME = 'PROVENANCE'
in the extension headerThe following table gives examples of attributes that may be applicable to an HLSP collection.
Field Name | Example Value | Description |
---|---|---|
FILE_ID | 'ockp11020 ' | File name or observatory-unique identifier of the contributing observation. For products from MAST missions, provide the Observation ID so that the contributing data may be linked within MAST. |
DATE-BEG | '2021-01-05T12:34:56.78' | ISO 8601-formatted date-time string for observation start |
DATE-END | '2021-01-05T12:39:56.78' | ISO 8601-formatted date-time string for observation end |
DISPRSR | 'G140L' | Name of dispersing optical element used |
FILTER | 'F25ND' | Name of (possibly passband limiting) filter used |
INSTRUME | 'STIS' | Name of instrument used |
RADESYS | 'ICRS' | Coordinate reference frame |
TELESCOP | 'HST' | Name of telescope used |
XPOSURE | 300 | Total duration of exposure in sec, exclusive of dead-time |