Home | News | Docs | WCS | Samples | Libraries | Viewers | Utilities | Keywords | Conventions | Resources
Registered FITS Convention (Under Review)
The HIERARCH Keyword Convention
- Description: Under this keyword convention, as originally defined by ESO, bytes 10 through 80 of the HIERARCH keyword record contain a series of ASCII strings, or tokens, that serve to hierarchically classify the keyword, followed by an equals sign (``='') which is in turn followed by the keyword value field. An optional comment field may follow the value field. The value and comment fields conform to the rules for free-format keywords, as defined in the FITS Standard document.
The following is an example of this convention,
HIERARCH ESO INS OPTI-3 ID = 'ESO#427 ' / Optical element identifierThe hierarchical keywords can be mapped into descriptor names by concatenating the hierarchical tokens together, separating them with the full stop character. For example, the hierarchical keyword shown above corresponds to the descriptor name ESO.INS.OPTI-3.ID.This ESO convention has been generalized to support keyword names longer than 8 characters, or which contain ASCII characters that would otherwise be prohibited. Some examples are shown below:
HIERARCH LongKeyword = 47.5 / keyword has > 8 characters and mixed case HIERARCH XTE$TEMP = 98.6 / This keyword contains the '$' characterSee the full documentation (available below) for the complete set of rules and recommendations regarding the use of this convention.
- Submitted: Sept 2007
- Registered: TBD
- Date and Place of First Usage: circa 1990, ESO (the European Organization for Astronomical Research in the Southern Hemisphere)
- Extent of Usage: Extensively used in FITS data files generated by ESO. This keyword convention is supported by the MIDAS data analysis system and by the CFITSIO FITS I/O library.
- Full Documentation: PDF format, Postscript format
- Sample FITS File: fors.fits
- Sample Header Listing: fors.txt
Home | News | Docs | WCS | Samples | Libraries | Viewers | Utilities | Keywords | Conventions | Resources
Last revised: Monday, 20-Aug-2007 16:13:03 EDT
Contact us: fits @ fits.gsfc.nasa.gov
Hosted by: The HEASARC (High Energy Astrophysics Science Archive Research Center)
Responsible NASA representative: Dr. William D. Pence Privacy, Security & Accessibility Statements. Download the PDF reader.