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FITS Standard Document

The official reference document that defines the requirements for FITS format data files.

Version 4.0 (13 August 2018): Latest language-edited PDF version,   

This latest version of the FITS Standard document was formally approved by the IAU FITS Working Group on 22 July 2016. The main difference from the previous Version 3 of the document is that a number of FITS conventions are now officially recognized, including conventions for representing Time world coordinates, and conventions for compressing FITS images and tables. A complete list of all the changes can be found in appendices H.3 and H.4 of the document.

In addition, the language style in the document has been extensively edited to provide more consistent word capitalization, hyphenation, punctuation, and other typographical issues. (Thanks to Malcolm Currie and Lucio Chiappetti for performing these painstaking edits.) This final 'language-edited' version of the FITS Standard was formally approved on 13 August 2018. The change summary page describes the changes that were made during the editing process.

Version 4 before the language editing (22 July 2016): PDF file

Version 3.0 (July 2008):
Published version:     in Astronomy and Astrophysics, Volume 524 (December 2010)

Latest PDF document maintained by the IAU FITS Working Group (November 2010)

Other related documents:

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:

Other related documents:

Version NOST 100-2.0 (March 1999):    PDF format,    Postscript format

Latex source files: fits_standard20.tex, nost.sty, ieee1.eps, ieee2.eps, fits_standard20.ind

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.

Version NOST 100-1.2 (April 1998):    PDF format,    Postscript format

This version adds the Image and Binary Table standard extensions. List of changes between v1.1 and v1.2.

Latex source files: fits_standard.tex, nost.sty, ieee1.eps, ieee2.eps, fits_standard.ind

Version NOST 100-1.1 (September 29 1995):    Postscript format,    latex source

Version NOST 100-1.0 (June 1993):    PDF format,    Postscript format,    NOST announcement

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