The FITS Standard is the definitive reference document that describes all the requirements of the FITS format. It is more than 100 pages long and has sections covering:
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FITS Standard Document
- FITS File Organization
- Header Keywords
- Data Representaion
- Random Groups Structure
- Image Extensions
- ASCII Table Extensions
- Binary Table Extensions
- World Coordinate Systems
Latest: Version 3.0 (July 2008):    PDF format,    Postscript format
Web HTML version - Note: this Web version was created from the PDF document. It does not exactly reproduce some of the typographical features of the original document, such as the italizied font that is used to emphasize the words "must", "should", "recommended", etc.Other related documents:
- Annotated file showing the differences between Version 3.0 and 2.1b (not 100% complete): PDF format, postscript format
- Initial summary of the changes in version 3.0, as compared with version 2.1b: PDF format, postscript format
Some of these recommendations were modified in response to public comments.- Technical Panel's response to the public comments on the proposed changes: PDF format, postscript format
- Original latex source document
- WCSfig.eps postscript figure
- Latex iaufwg.sty , epsf.sty , and deluxetable.sty style files.
- Latex index file
Version 2.1b (December 2005):    PDF format,    Postscript format
Main changes in version 2.1b compared to the previous NOST 100-2.0 version are:
- Added support for 64-bit integer primary arrays and image extensions with BITPIX = 64, for 64-bit integer columns in binary tables with TFORMn = 'K', and for 64-bit descriptor columns in binary tables with TFORMn = 'Q'. This was approved by the IAU FITS Working Group in December 2005.
- The description of the TDIMn keyword convention and the variable-length array convention that used to be in the unofficial appendices B.1 and B.2 have been moved into the main body of the document, to reflect the offical approval of these 2 conventions by the IAU FITS Working Group in April 2005.
- The title page lists the 'IAU FITS Working Group' instead of the NOST as the originator of the document.
- A short 'Preface to Version 2.1b' has been added.
- A clarification on the meaning of the word 'deprecated' has been added to section 7.0 (Random Groups). This modification was approved by the IAU FWG in October 2000 when it adopted the NOST Standard as the IAU FITS Standard.
Other related documents:
Version NOST 100-2.0 (March 1999):    PDF format,    Postscript format
Other related documents:
This version of the Standard was published in the Astronomy & Astrophysics scientific journal in September 2001. This published version was endorsed by the IAU FITS Working Group in October 2000 and is identical to the original NOST document except for the addition of 2 introductory sections on the history of FITS and on the process that lead to the creation of the NOST document. There were also 2 minor clarifications on a) the interpretation of the word "deprecated" and b) the usage of the TDIMn keyword with variable length array columns.
- Original latex source document
- Latex nost.sty file
- ieee1.eps and ieee2.eps postscript figures
- Latex index file
Version NOST 100-1.0 (June 1993):    PDF format,    Postscript format
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Last revised: Monday, 21-Jul-2008 14:16:24 EDT
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