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HLSP Metadata

Header Metadata

Metadata, or data that describe data, are required for documenting essential attributes of the data products, such as provenance, world coordinates, and data origin. In FITS files, metadata are expressed as header keywords. They facilitate an automated data quality assessment, and provide structured attributes that enable MAST users to search for and identify data products. In general HLSP providers may include almost any header keyword they deem appropriate for their own use. But in order to be useful for archival users, science data products in HLSP collections must include specific, named keyword records with values and locations that are prescribed below. HLSPs would be even more useful if the science headers also include certain recommended keywords to establish a complete provenance.

If your data were obtained with HST or other NASA missions and you did not radically alter the headers (apart from updates to reflect the processing to create your HLSP collectioni), most of the needed metadata may already be present. Prior to submitting your HLSP collection to MAST, please check that the required metadata are present. A user tool to verify the required metadata will be added in the future.

The specific keywords that are required depend upon the science content and organization of the data. Follow the links below for your specific content:

Data Simulations

Generally, data simulations should include the same metadata that apply to the data product that is being simulated. However, it is essential that users of the simulations (including software applications) be able to distinguish between simulated and observed data. Therefore all simulated data must include the following keyword in the primary header (PHDU) in FITS files:

  • SIMULATD = 'T'

Continued-String Keywords

The (pending) revision of the FITS Standard allows for continued-string (or long-string) keyword records. These are string-valued keywords, with values that are too long to be defined within the character limitation of a single keyword record. This feature must not be used with any of the keywords designated as mandatory or reserved in the FITS Standard, but otherwise may be used without restriction in HLSP science files.